Revert "CI: Work around a weird bug in Yarn v1.x"

This reverts commit 12c276b.

Revert a now-unnecessary workaround.

Amazingly, this issue has been avoided in the latest npm versions,
as npm have restored the files Yarn 1.x rather over-optimistically
required npm to have.

NodeJS has in turn bundled these versions of npm with the fixes before
the final minor/patch release of every major version of NodeJS.

This is effectively a solved issue if you use the latest patch versions
of NodeJS. No more incompatibility with Yarn 1.x in these narrow cases.

(Admittedly, the Yarn 1.x issue was due to a genuine bug in Yarn 1.x,
not a deliberate thing from the Yarn authors I don't think).

.github/workflows/CI.yml

@@ -56,11 +56,7 @@ jobs:
         run: python3 -m pip install setuptools
 
       - name: Install dependencies
-        run: |
-          # Yarn v1.x needs global node-gyp available if npm 9.7.2+ is the global npm version,
-          # or else postinstall scripts for this repo won't run. It's a long story. And it's a "won't fix" bug in Yarn v1.x.
-          yarn global add [email protected]
-          yarn install
+        run: yarn install
 
       - if: "!contains(matrix.os, 'windows')"
         name: Run tests 👩🏾‍💻