Use "after" SHA in a push, not "before"

Author: MahdiBM

.github/workflows/swift_matrix.yml

@@ -119,7 +119,7 @@ jobs:
       uses: actions/cache/restore@v4
       with:
         path: .build
-        key: "${{ inputs.cache_key_prefix }}${{ github.event.repository.name }}-build-${{ matrix.swift.swift_version }}-${{ runner.os }}-${{ (github.event.pull_request.base.sha != null) && github.event.pull_request.base.sha || github.event.before }}"
+        key: "${{ inputs.cache_key_prefix }}${{ github.event.repository.name }}-build-${{ matrix.swift.swift_version }}-${{ runner.os }}-${{ (github.event.pull_request.base.sha != null) && github.event.pull_request.base.sha || github.event.after }}"
         restore-keys: "${{ inputs.cache_key_prefix }}${{ github.event.repository.name }}-build-${{ matrix.swift.swift_version }}-${{ runner.os }}"
 
     - name: Run matrix job
@@ -141,4 +141,4 @@ jobs:
       uses: actions/cache/save@v4
       with:
         path: .build
-        key: "${{ inputs.cache_key_prefix }}${{ github.event.repository.name }}-build-${{ matrix.swift.swift_version }}-${{ runner.os }}-${{ (github.event.pull_request.base.sha != null) && github.event.pull_request.base.sha || github.event.before }}"
+        key: "${{ inputs.cache_key_prefix }}${{ github.event.repository.name }}-build-${{ matrix.swift.swift_version }}-${{ runner.os }}-${{ (github.event.pull_request.base.sha != null) && github.event.pull_request.base.sha || github.event.after }}"