chore(build): update to Gradle 8.12 and set CI to use JDK 17 (#308)

Upgraded the build system to Gradle 8.12 and updated the CI pipeline to use JDK 17 for improved compatibility and performance.

imgui-binding/build.gradle

@@ -15,8 +15,9 @@ java {
 }
 
 dependencies {
-    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.11.3'
-    testImplementation 'org.junit.jupiter:junit-jupiter-engine:5.11.3'
+    testImplementation("org.junit.jupiter:junit-jupiter-api:5.11.3")
+    testImplementation("org.junit.jupiter:junit-jupiter-engine:5.11.3")
+    testRuntimeOnly("org.junit.platform:junit-platform-launcher")
 }
 
 test {
@@ -53,7 +54,7 @@ jar {
 processResources {
     filesMatching('**/imgui-java.properties') {
         filter(ReplaceTokens, tokens: [
-                'version': project.version
+                'version': version
         ])
     }
 }