github/workflows: remove xcode 13.0 to xcode 13.1 override

Thankfully, this version is no longer the default on any of the
macOS runners.

Effectively reverts a76527772e .

.github/workflows/build.yml

@@ -75,16 +75,6 @@ jobs:
     steps:
       - uses: actions/checkout@v2
 
-      - name: Override Xcode 13.0 if it's the default toolchain
-        run: |
-          XCODE_PATH="$(xcode-select -p)"
-          case "${XCODE_PATH}" in
-            *Xcode_13.0*)
-              sudo xcode-select -s "/Applications/Xcode_13.1.app"
-              echo "Updated Xcode path ${XCODE_PATH} -> $(xcode-select -p)"
-              ;;
-          esac
-
       - name: Install dependencies
         run: |
           brew update