GHA: Update to actions/checkout@v4

Author: nicowilliams

.github/actions/get-gtest/action.yml

@@ -40,7 +40,7 @@ runs:
         var: GTEST_VERSION
 
     - name: 'Checkout GTest source'
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
       with:
         repository: google/googletest
         ref: 'v${{ steps.version.outputs.value }}'

.github/actions/get-jtreg/action.yml

@@ -52,7 +52,7 @@ runs:
         key: jtreg-${{ steps.version.outputs.value }}
 
     - name: 'Checkout the JTReg source'
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
       with:
         repository: openjdk/jtreg
         ref: jtreg-${{ steps.version.outputs.value }}

.github/workflows/build-linux.yml

@@ -89,7 +89,7 @@ jobs:
           sudo add-apt-repository ppa:ubuntu-toolchain-r/test
 
       - name: 'Checkout the JDK source'
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: 'Get the BootJDK'
         id: bootjdk