fix: 整体降级到 Java 17 + Gradle 8.1 以兼容 ForgeGradle 5.1.x

- gradle.properties: java_version=21 -> 17
- gradle-wrapper: 8.12.1 -> 8.1
- .github/workflows/gradle.yml: setup-java 21 -> 17
- ForgeGradle 5.1.x 需要 Gradle 8.1 及 Java 17

Author: Meeuyt

.github/workflows/gradle.yml

@@ -28,7 +28,7 @@ jobs:
         uses: actions/setup-java@v4
         with:
           distribution: temurin
-          java-version: "21"
+          java-version: "17"
           cache: gradle
 
       # 可选：更安全，防止 wrapper 被篡改（不想要可删）

gradle.properties

@@ -4,7 +4,7 @@
 version=2.5.6.3-SNAPSHOT
 group=cn.coostack
 artifact=cooparticlesapi
-java_version=21
+java_version=17
 # Common
 minecraft_version=1.21.1
 mod_name=CooParticlesAPI

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.12.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.1-bin.zip
 networkTimeout=10000
 validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME