[ci] Update GitHub Actions to latest major release

Fix deprecation warning for Node20.js that will stop working
in June.

Author: gruenich

.github/workflows/check_diff.yml

@@ -39,7 +39,7 @@ jobs:
 
     steps:
     - name: checkout
-      uses: actions/checkout@v4
+      uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
     - name: Build check_diff binary
       working-directory: ./check_diff

.github/workflows/integration.yml

@@ -64,7 +64,7 @@ jobs:
 
     steps:
     - name: checkout
-      uses: actions/checkout@v4
+      uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
       # Run build
     - name: install rustup

.github/workflows/linux.yml

@@ -26,7 +26,7 @@ jobs:
 
     steps:
     - name: checkout
-      uses: actions/checkout@v4
+      uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
       # Run build
     - name: install rustup

.github/workflows/mac.yml

@@ -22,7 +22,7 @@ jobs:
 
     steps:
     - name: checkout
-      uses: actions/checkout@v4
+      uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
       # Run build
     - name: install rustup

.github/workflows/rustdoc_check.yml

@@ -11,7 +11,7 @@ jobs:
     name: rustdoc check
     steps:
     - name: checkout
-      uses: actions/checkout@v4
+      uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
     - name: install rustup
       run: |

.github/workflows/upload-assets.yml

@@ -31,7 +31,7 @@ jobs:
             target: x86_64-pc-windows-msvc
     runs-on: ${{ matrix.os }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
         # Run build
       - name: install rustup

.github/workflows/windows.yml

@@ -33,7 +33,7 @@ jobs:
     - name: disable git eol translation
       run: git config --global core.autocrlf false
     - name: checkout
-      uses: actions/checkout@v4
+      uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
       # Run build
     - name: Install Rustup using win.rustup.rs