ci: downgrade java version to 17 on release and nightly build

This may solve the build failure because of recent changes.

Author: WhiredPlanck

.github/workflows/nightly-ci.yml

@@ -21,7 +21,7 @@ jobs:
         uses: actions/setup-java@v4
         with:
           distribution: "temurin"
-          java-version: 21
+          java-version: 17
           # will restore cache of dependencies and wrappers
           cache: 'gradle'
 

.github/workflows/release-ci.yml

@@ -20,7 +20,7 @@ jobs:
         uses: actions/setup-java@v4
         with:
           distribution: "temurin"
-          java-version: 21
+          java-version: 17
           # will restore cache of dependencies and wrappers
           cache: 'gradle'