Use pull request HEAD commit instead of pr/merge commit

By default action uses merge commit (created with github account
data). This may cause authors test to fail when contributor's info
differs from github account (eg contributor prefers cpan email when
contributing to perl)

.github/workflows/testsuite.yml

@@ -37,6 +37,7 @@ jobs:
       - uses: actions/checkout@v2
         with:
           fetch-depth: 1000
+          ref: ${{ github.event.pull_request.head.sha }}
       - name: git setup
         run: |
           echo "Pull request authors"
@@ -91,6 +92,7 @@ jobs:
       - uses: actions/checkout@v2
         with:
           fetch-depth: 0
+          ref: ${{ github.event.pull_request.head.sha }}
       - name: git cfg + fetch tags
         run: |
           git config diff.renameLimit 999999
@@ -156,6 +158,8 @@ jobs:
           sudo apt-get update
           sudo apt-get install -y libgdbm-dev libdb-dev
       - uses: actions/checkout@v2
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
       - name: git cfg + fetch tags
         run: |
           git config diff.renameLimit 999999
@@ -251,6 +255,8 @@ jobs:
           sudo apt-get update
           sudo apt-get install -y libgdbm-dev libdb-dev
       - uses: actions/checkout@v2
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
       - name: git cfg + fetch tags
         run: |
           git config diff.renameLimit 999999
@@ -304,6 +310,8 @@ jobs:
 
     steps:
       - uses: actions/checkout@v2
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
       - name: Configure
         run: |
           export SDK=/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.15.sdk
@@ -334,6 +342,8 @@ jobs:
     steps:
       - run: git config --global core.autocrlf false
       - uses: actions/checkout@v2
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
       #- name: Install clcache
       #  shell: cmd
       #  run: |
@@ -390,6 +400,8 @@ jobs:
     steps:
       - run: git config --global core.autocrlf false
       - uses: actions/checkout@v2
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
       - name: Set up Perl build environment
         run: |
           # skip installing perl if it is already installed.
@@ -513,6 +525,8 @@ jobs:
           sudo apt-get update
           sudo apt-get install -y libgdbm-dev libdb-dev
       - uses: actions/checkout@v2
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
       - name: git cfg + fetch tags
         run: |
           git config diff.renameLimit 999999
@@ -565,6 +579,8 @@ jobs:
           sudo apt-get update
           sudo apt-get install -y libgdbm-dev libdb-dev
       - uses: actions/checkout@v2
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
       - name: git cfg + fetch tags
         run: |
           git config diff.renameLimit 999999
@@ -614,6 +630,8 @@ jobs:
           sudo apt-get update
           sudo apt-get install -y libgdbm-dev libdb-dev
       - uses: actions/checkout@v2
+        with:
+          ref: ${{ github.event.pull_request.head.sha }}
       - name: git cfg + fetch tags
         run: |
           git config diff.renameLimit 999999