Fix JDK20 env variable declaration in CI pipeline

See gh-30185

Author: bclozel

ci/scripts/check-project.sh

@@ -4,6 +4,6 @@ set -e
 source $(dirname $0)/common.sh
 
 pushd git-repo > /dev/null
-./gradlew -Dorg.gradle.internal.launcher.welcomeMessageEnabled=false -Porg.gradle.java.installations.fromEnv=JDK17,JDK19 \
+./gradlew -Dorg.gradle.internal.launcher.welcomeMessageEnabled=false -Porg.gradle.java.installations.fromEnv=JDK17,JDK20 \
   -PmainToolchain=${MAIN_TOOLCHAIN} -PtestToolchain=${TEST_TOOLCHAIN} --no-daemon --max-workers=4 check
 popd > /dev/null