Let make add build/twine to a virtual environment

Makefile

@@ -12,6 +12,11 @@ release: clean
 	echo "HEAD SHA       = $$(git rev-parse head)"
 	echo "Latest tag SHA = $$(git tag | sort -nr | head -n1 | xargs git rev-parse)"
 	@test "$$(git rev-parse head)" = "$$(git tag | sort -nr | head -n1 | xargs git rev-parse)"
+
+	# If we're in a virtual environment, add build tools
+	test -z "$$VIRTUAL_ENV" || pip install -U build twine
+
+	# Do the release
 	make force_release
 
 force_release: clean

README.md

@@ -188,13 +188,15 @@ Please have a look at the [contributions file][contributing].
 
 ### How to make a new release
 
-- Update/verify the **version** in the `VERSION` file
-- Update/verify that the `doc/source/changes.rst` changelog file was updated
-- Commit everything
-- Run `git tag -s <version>` to tag the version in Git
-- Run `make release`
+- Update/verify the **version** in the `VERSION` file.
+- Update/verify that the `doc/source/changes.rst` changelog file was updated.
+- Commit everything.
+- Run `git tag -s <version>` to tag the version in Git.
+- *Optionally* create and activate a [virtual environment](https://packaging.python.org/en/latest/guides/installing-using-pip-and-virtual-environments/#creating-a-virtual-environment) using `venv` or `virtualenv`.\
+(If run in a virtual environment, the next step will automatically take care of installing `build` and `twine` in it.)
+- Run `make release`.
 - Close the milestone mentioned in the _changelog_ and create a new one. _Do not reuse milestones by renaming them_.
-- Got to [GitHub Releases](https://github.com/gitpython-developers/GitPython/releases) and publish a new one with the recently pushed tag. Generate the changelog.
+- Go to [GitHub Releases](https://github.com/gitpython-developers/GitPython/releases) and publish a new one with the recently pushed tag. Generate the changelog.
 
 ### How to verify a release (DEPRECATED)
 

test-requirements.txt

@@ -1,5 +1,4 @@
 black
-build
 coverage[toml]
 ddt>=1.1.1, !=1.4.3
 mypy