Introduce pre-build step

Author: hannesa2

.github/workflows/BuildPR.yml

@@ -18,5 +18,7 @@ jobs:
           submodules: true
       - name: Set XCode Version
         run: sudo xcode-select -s /Applications/${{ matrix.xcode }}.app
+      - name: pre build
+        run: script/bootstrap && script/update_libgit2
       - name: Build project
         run: xcodebuild -workspace ObjectiveGitFramework.xcworkspace -scheme "ObjectiveGit Mac" archive ARCHS="x86_64 arm64"