Use java 21

Author: evan10s

.github/workflows/build.yml

@@ -24,7 +24,7 @@ jobs:
     - name: Set up JDK
       uses: actions/setup-java@v4
       with:
-        java-version: '17'
+        java-version: '21'
         distribution: 'corretto'
         cache: gradle
 

.github/workflows/internal-test-release.yml

@@ -23,7 +23,7 @@ jobs:
     - name: Set up JDK
       uses: actions/setup-java@v4
       with:
-        java-version: '17'
+        java-version: '21'
         distribution: 'corretto'
         cache: gradle