[ci] fix merge commit extraction for ci

.github/workflows/clang-tidy.yml

@@ -12,7 +12,7 @@ jobs:
       id: pr
     - uses: actions/checkout@v4
       with:
-        ref: ${{fromJSON(steps.pr.outputs.result).merge_commit_sha}}
+        ref: ${{steps.pr.outputs.merge_commit_sha}}
 
     # Run clang-tidy
     - uses: ZedThree/clang-tidy-review@v0.17.1

.github/workflows/codeql-analysis.yml

@@ -40,7 +40,7 @@ jobs:
       id: pr
     - uses: actions/checkout@v4
       with:
-        ref: ${{fromJSON(steps.pr.outputs.result).merge_commit_sha}}
+        ref: ${{steps.pr.outputs.merge_commit_sha}}
 
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL

.github/workflows/fuzzing.yml

@@ -22,7 +22,7 @@ jobs:
         id: pr
       - uses: actions/checkout@v4
         with:
-          ref: ${{fromJSON(steps.pr.outputs.result).merge_commit_sha}}
+          ref: ${{steps.pr.outputs.merge_commit_sha}}
 
       - name: Build fuzzers (${{ matrix.sanitizer }})
         id: build