fix: use Package.swift for CI cache keys instead of Package.resolved

Author: coenttb

.github/workflows/ci.yml

@@ -40,7 +40,7 @@ jobs:
         uses: actions/cache@v4
         with:
           path: .build
-          key: ${{ runner.os }}-xcode-${{ matrix.xcode }}-spm-${{ hashFiles('Package.resolved') }}
+          key: ${{ runner.os }}-xcode-${{ matrix.xcode }}-spm-${{ hashFiles('Package.swift') }}
           restore-keys: |
             ${{ runner.os }}-xcode-${{ matrix.xcode }}-spm-
             ${{ runner.os }}-spm-