Do not run test suite on Java 8, 11

Author: tokuhirom

.github/workflows/gradle.yml

@@ -17,7 +17,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        java: [ '8', '11', '17' ] # We want to test on LTSs.
+        java: [ '17' ] # We want to test on LTSs.
     steps:
     - name: actions/setup-java@v3 (JDK ${{ matrix.java }})
       uses: actions/setup-java@v3
@@ -38,11 +38,11 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 10
     steps:
-    - name: actions/setup-java@v3 (JDK 1.8)
+    - name: actions/setup-java@v3 (JDK 17)
       uses: actions/setup-java@v3
       with:
         distribution: 'temurin'
-        java-version: 8
+        java-version: 17
         architecture: x64
     - uses: actions/checkout@v3
     - run: |
@@ -56,11 +56,11 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 10
     steps:
-    - name: actions/setup-java@v3 (JDK 1.8)
+    - name: actions/setup-java@v3 (JDK 1.17)
       uses: actions/setup-java@v3
       with:
         distribution: 'temurin'
-        java-version: 8
+        java-version: 17
         architecture: x64
     - uses: actions/checkout@v3
     - run: |
@@ -75,11 +75,11 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 10
     steps:
-    - name: actions/setup-java@v3 (JDK 1.8)
+    - name: actions/setup-java@v3 (JDK 17)
       uses: actions/setup-java@v3
       with:
         distribution: 'temurin'
-        java-version: 8
+        java-version: 17
         architecture: x64
     - uses: actions/checkout@v3
     - run: |

.github/workflows/pom-validation.yml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        java: [ '8', '11', '17' ] # We want to test on LTSs.
+        java: [ '17' ] # We want to test on LTSs.
     steps:
     - name: actions/setup-java@v3 (JDK ${{ matrix.java }})
       uses: actions/setup-java@v3