Return to official LCOV releases on macOS

Now that [LCOV v2.3][] has been released, with the necessary
regex typo fix ([b34c844][]).

[LCOV v2.3]: https://github.com/linux-test-project/lcov/releases/tag/v2.3
[b34c844]: linux-test-project/lcov@b34c844

.github/workflows/build.yaml

@@ -216,8 +216,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - name: Install lcov
-        run: brew install lcov --head # \todo Remove when lcov commit b34c844 is released.
-        # \todo See https://github.com/linux-test-project/lcov/commit/b34c84431a97b49e55785286fa05e9a95b873920
+        run: brew install lcov
       - name: Install Qt
         uses: jurplel/install-qt-action@v4
         with: