ci: set GOTOOLCHAIN=local for unit tests

Users may build our library with GOTOOLCHAIN=local. If they do, and our
go.mod file specifies a newer Go version than their local toolchain, their
build will break. Run our tests with GOTOOLCHAIN=local to ensure that
our library builds with all of the Go versions we claim to support,
without having to download a newer one.

.github/workflows/smoke-tests.yml

@@ -70,6 +70,13 @@ jobs:
  # Run go mod tidy to ensure that all go.mod and go.sum files are up-to-date.
  name: 'go mod tidy smoke test'
  runs-on: ubuntu-latest
+ env:
+ # Users may build our library with GOTOOLCHAIN=local. If they do, and our
+ # go.mod file specifies a newer Go version than their local toolchain, their
+ # build will break. Run our tests with GOTOOLCHAIN=local to ensure that
+ # our library builds with all of the Go versions we claim to support,
+ # without having to download a newer one.
+ GOTOOLCHAIN: local
  steps:
  - uses: actions/checkout@v4
  with:

.github/workflows/unit-integration-tests.yml

@@ -13,6 +13,12 @@ on:
 
 env:
  DD_APPSEC_WAF_TIMEOUT: 1m # Increase time WAF time budget to reduce CI flakiness
+ # Users may build our library with GOTOOLCHAIN=local. If they do, and our
+ # go.mod file specifies a newer Go version than their local toolchain, their
+ # build will break. Run our tests with GOTOOLCHAIN=local to ensure that
+ # our library builds with all of the Go versions we claim to support,
+ # without having to download a newer one.
+ GOTOOLCHAIN: local
 
 jobs:
  copyright:

internal/exectracetest/go.mod

@@ -2,8 +2,6 @@ module gopkg.in/DataDog/dd-trace-go.v1/internal/exectracetest
 
 go 1.21
 
-toolchain go1.21.0
-
 require (
  github.com/google/pprof v0.0.0-20230817174616-7a8ec2ada47b
  github.com/mattn/go-sqlite3 v1.14.18