fix: remove subprojects build config, add group and version (#40)

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<!-- Provide a brief summary of the changes -->

Remove subprojects configuration.

## Description
<!-- Provide a detailed description of the changes -->

Missed from #39. Also added groupId and version in build file (may be
needed for GH package publish).

## References
<!-- Provide a list of any applicable references here (GitHub Issue,
[OpenFGA RFC](https://github.com/openfga/rfcs), other PRs, etc..) -->

## Review Checklist
- [x] I have clicked on ["allow edits by
maintainers"](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/allowing-changes-to-a-pull-request-branch-created-from-a-fork).
- [ ] I have added documentation for new/changed functionality in this
PR or in a PR to [openfga.dev](https://github.com/openfga/openfga.dev)
[Provide a link to any relevant PRs in the references section above]
- [x] The correct base branch is being used, if not `main`
- [ ] I have added tests to validate that the change in functionality is
working as expected

build.gradle

@@ -15,6 +15,9 @@ plugins {
 
 apply from: 'publish.gradle'
 
+group = 'dev.openfga'
+version = '0.0.1'
+
 java {
     sourceCompatibility = 17
     targetCompatibility = 17
@@ -50,50 +53,31 @@ test {
     useJUnitPlatform()
 }
 
-subprojects {
-    apply plugin: 'java'
-    apply plugin: 'com.diffplug.spotless'
-    apply plugin: 'jacoco'
-
-    group = "dev.openfga"
-    version = "0.0.1-SNAPSHOT"
-
-    java {
-        sourceCompatibility = 17
-        targetCompatibility = 17
-    }
-
-    repositories {
-        mavenCentral()
+spotless {
+    format 'misc', {
+        // define the files (e.g. '*.gradle', '*.md') to apply `misc` to
+        target '.gitignore', '*.gradle'
+        // define the steps to apply to those files
+        trimTrailingWhitespace()
+        indentWithSpaces()
+        endWithNewline()
     }
-
-    spotless {
-        format 'misc', {
-            // define the files (e.g. '*.gradle', '*.md') to apply `misc` to
-            target '.gitignore', '*.gradle'
-            // define the steps to apply to those files
-            trimTrailingWhitespace()
-            indentWithSpaces()
-            endWithNewline()
-        }
-        java {
-            palantirJavaFormat()
-            removeUnusedImports()
-            importOrder()
-        }
+    java {
+        palantirJavaFormat()
+        removeUnusedImports()
+        importOrder()
     }
+}
 
-    test {
-        finalizedBy jacocoTestReport // report is always generated after tests run
-    }
-
-    jacocoTestReport {
-        // tests are required to run before generating a JaCoCo coverage report.
-        dependsOn test
-    }
+test {
+    finalizedBy jacocoTestReport // report is always generated after tests run
+}
 
-    tasks.register('fmt') {
-        dependsOn 'spotlessApply'
-    }
+jacocoTestReport {
+    // tests are required to run before generating a JaCoCo coverage report.
+    dependsOn test
+}
 
+tasks.register('fmt') {
+    dependsOn 'spotlessApply'
 }