ci: fix lint, markdown links, and build (#282)

Closes #269,
#275,
#279,
#222 (b/c no longer relevant)

Note: this PR removes code coverage. If we want it back, IMO it should
be a separate workflow.

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

## Release Notes

- **New Features**
- Introduced new Makefile targets for linting and markdown link
checking.
  
- **Bug Fixes**
- Improved test reliability by ensuring correct variable capture in test
cases.

- **Documentation**
- Updated README files for clarity and accuracy, including installation
instructions and resource links.

- **Chores**
	- Updated Go version in project configuration.
- Streamlined workflow configurations for building and testing
processes.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

.github/workflows/go.yml

@@ -12,32 +12,23 @@ jobs:
     runs-on: ubuntu-latest
     steps:
 
-      - name: Set up Go 1.21
+      - name: Check out code
+        uses: actions/checkout@v4
+
+      - name: Set up Go
         uses: actions/setup-go@v5
         with:
-          go-version: 1.21
+          go-version-file: 'go.mod'
         id: go
 
-      - name: Check out code into the Go module directory
-        uses: actions/checkout@v4
-
       - name: Get dependencies
         run: |
           go get -v -t -d ./...
 
-      - name: Format
-        run: diff -u <(echo -n) <(gofmt -d .)
-
       - name: Build
         run: go build -v .
 
-      - name: Test and Coverage
+      - name: Test
         run: |
           export PATH=$PATH:$(go env GOPATH)/bin
-          go test -v -coverpkg=./... -covermode=atomic -coverprofile coverage.txt ./...
-
-      - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v4
-        with:
-          token: ${{ secrets.CODECOV_TOKEN }}
-          fail_ci_if_error: true
+          go test -v ./...

.github/workflows/lint.yml

@@ -22,7 +22,7 @@ jobs:
             .sum
       - uses: golangci/golangci-lint-action@v6
         with:
-          version: latest
+          version: v1.61.0
           args: --timeout 10m
         if: env.GIT_DIFF
 

.golangci.yml

@@ -4,7 +4,7 @@ run:
 
 linters:
   enable:
-    - exportloopref
+    - copyloopvar
     - gofumpt
     - misspell
     - revive

Makefile

@@ -0,0 +1,13 @@
+## lint: Run all linters; golangci-lint, markdownlint.
+lint:
+	@echo "--> Running golangci-lint"
+	@golangci-lint run
+	@echo "--> Running markdownlint"
+	@markdownlint --config .markdownlint.yaml '**/*.md'
+.PHONY: lint
+
+## markdown-link-check: Check all markdown links.
+markdown-link-check:
+	@echo "--> Running markdown-link-check"
+	@find . -name \*.md -print0 | xargs -0 -n1 markdown-link-check
+.PHONY: markdown-link-check

README.md

@@ -1,10 +1,8 @@
 # Namespaced Merkle Tree (NMT)
 
-![Go version](https://img.shields.io/badge/go-1.21-blue.svg)
 [![Go Reference](https://pkg.go.dev/badge/github.com/celestiaorg/nmt.svg)](https://pkg.go.dev/github.com/celestiaorg/nmt)
 ![golangci-lint](https://github.com/celestiaorg/nmt/workflows/lint/badge.svg)<!-- it retrieves the lint workflow status badge for the default branch i.e., main, for a different branch, specify the branch parameter in the URL() -->
 ![Go](https://github.com/celestiaorg/nmt/workflows/Go/badge.svg)
-![codecov.io](https://codecov.io/github/celestiaorg/nmt/coverage.svg?branch=main)
 
 A Namespaced Merkle Tree is
 > [...] an ordered Merkle tree that uses a modified hash function

go.mod

@@ -1,6 +1,6 @@
 module github.com/celestiaorg/nmt
 
-go 1.21
+go 1.23
 
 require (
 	github.com/gogo/protobuf v1.3.2

nmt_quint_model/README.md

@@ -61,11 +61,9 @@ While this is not necessary, it is of great help when writing models.
 
 ## Basic resources
 
-- a sequence of very gentle and fun tutorials
-[here](https://github.com/informalsystems/quint/blob/main/tutorials/README.md)
-- language [cheatsheet](https://github.com/informalsystems/quint/blob/main/doc/quint-cheatsheet.pdf)
-- documentation for built-in operators
-[here](https://github.com/informalsystems/quint/blob/main/doc/builtin.md)
+- a sequence of [lessons](https://quint-lang.org/docs/lessons)
+- language [cheatsheet](https://quint-lang.org/quint-cheatsheet.pdf)
+- documentation for [built-in operators](https://quint-lang.org/docs/builtin)
 
 ## REPL
 

subrootpaths_test.go

@@ -132,7 +132,6 @@ func TestPathGeneration(t *testing.T) {
 	}
 
 	for _, tc := range tests {
-		tc := tc
 		t.Run(tc.desc, func(t *testing.T) {
 			paths, err := GetSubrootPaths(tc.input.squareSize, tc.input.startNode, tc.input.length)
 			if !reflect.DeepEqual(pathResult(paths), tc.want) {