[CI] Do not cache SPM due to GitHub cache-related issues (#566)

Author: testableapple

.github/actions/xcode-cache/action.yml

@@ -7,13 +7,6 @@ runs:
       shell: bash
     - run: echo "$HOME/.mint/bin" >> $GITHUB_PATH
       shell: bash
-    - name: Cache SPM
-      uses: actions/cache@v4
-      id: spm-cache
-      with:
-        path: spm_cache
-        key: ${{ env.IMAGE }}-spm-${{ hashFiles('**/Package.resolved') }}
-        restore-keys: ${{ env.IMAGE }}-spm-
     - uses: mikehardy/buildcache-action@v2
       with:
         cache_key: ${{ env.IMAGE }}-buildcache-