update all "checkout" actions to v7

Author: stephengold

.github/workflows/push-master.yml

@@ -18,7 +18,7 @@ jobs:
       - uses: actions/setup-node@v6
         with:
           node-version: 24.17.0
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - run: npm install --save-dev --save-exact antora
       - run: npx antora src/site/ci-playbook.yml
       - run: ./gradlew copyJavadocToSite --console=plain --stacktrace

.github/workflows/push.yml

@@ -14,7 +14,7 @@ jobs:
         with:
           distribution: 'zulu'
           java-version: 17
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - uses: gradle/actions/setup-gradle@v6
       - run: |
           ./gradlew -Pbt=Debug -Pflavor=Sp -Ptarget=Windows64 run build install \
@@ -32,7 +32,7 @@ jobs:
         with:
           distribution: 'zulu'
           java-version: 21
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - uses: gradle/actions/setup-gradle@v6
       - run: |
           ./gradlew -Pbt=Debug -Pflavor=Dp -Ptarget=Linux64 -Ptool=gcc run build install \
@@ -62,7 +62,7 @@ jobs:
         with:
           distribution: 'zulu'
           java-version: 21
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - run: g++ --version
       - uses: gradle/actions/setup-gradle@v6
       - run: |
@@ -94,7 +94,7 @@ jobs:
         with:
           distribution: 'zulu'
           java-version: 21
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - uses: gradle/actions/setup-gradle@v6
       - uses: maxim-lobanov/setup-xcode@v1
         with:
@@ -127,7 +127,7 @@ jobs:
         with:
           distribution: 'zulu'
           java-version: 21
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - uses: gradle/actions/setup-gradle@v6
       - uses: maxim-lobanov/setup-xcode@v1
         with:
@@ -160,7 +160,7 @@ jobs:
         with:
           distribution: 'zulu'
           java-version: 21
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - uses: gradle/actions/setup-gradle@v6
       - run: |
           ./gradlew -Pbt=Debug -Pflavor=Dp -Ptarget=Windows64 run build install \
@@ -192,7 +192,7 @@ jobs:
         with:
           distribution: 'zulu'
           java-version: 21
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - uses: gradle/actions/setup-gradle@v6
       - run: |
           ./gradlew -Pbt=Debug -Pflavor=Sp -Ptarget=Windows_ARM64 run build install \
@@ -225,7 +225,7 @@ jobs:
         with:
           distribution: 'zulu'
           java-version: 21
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - uses: gradle/actions/setup-gradle@v6
       - run: |
           cp android.gradle build.gradle
@@ -256,7 +256,7 @@ jobs:
         with:
           distribution: 'zulu'
           java-version: 21
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - run: sudo apt-get update
       - run: sudo apt install g++-9-arm-linux-gnueabihf
       - run: arm-linux-gnueabihf-g++-9 --version
@@ -289,7 +289,7 @@ jobs:
         with:
           distribution: 'zulu'
           java-version: 21
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - run: sudo apt-get update
       - run: sudo apt install g++-13-loongarch64-linux-gnu
       - run: loongarch64-linux-gnu-g++-13 --version
@@ -317,7 +317,7 @@ jobs:
         with:
           distribution: 'zulu'
           java-version: 26
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@v7
       - uses: gradle/actions/setup-gradle@v6
       - run: |
           ./gradlew -Pbt=Debug -Pflavor=Dp -Ptarget=Linux64 run build install \