fix: use shadow 7.1.2 — last AGP-compatible release on Plugin Portal

Shadow 8.x was never published under com.github.jengelman.gradle.plugins
(hence the original CI failure). Shadow 9.x explicitly blocks AGP projects.
The io.github.goooler.shadow 8.x fork lives on Maven Central, not the
Gradle Plugin Portal, requiring an extra repository that is undesirable.

7.1.2 is the last stable release under com.github.jengelman.gradle.plugins,
is present on the Gradle Plugin Portal, and works correctly with AGP.

Author: ivol

android/build.gradle

@@ -24,12 +24,12 @@ buildscript {
         gradlePluginPortal()
     }
     dependencies {
-        classpath 'com.gradleup.shadow:shadow-gradle-plugin:9.4.2'
+        classpath 'com.github.jengelman.gradle.plugins:shadow:7.1.2'
     }
 }
 
 apply plugin: 'com.android.library'
-apply plugin: 'com.gradleup.shadow'
+apply plugin: 'com.github.johnrengelman.shadow'
 
 def candidateMiniSdkRoots = [
     new File(projectDir, '../../core-service-layers-testing/mini-sdk/android'),
@@ -115,7 +115,7 @@ configurations {
     shadowed
 }
 
-tasks.register('shadowJar', com.gradleup.shadow.tasks.ShadowJar) {
+tasks.register('shadowJar', com.github.jengelman.gradle.plugins.shadow.tasks.ShadowJar) {
     archiveClassifier.set('shadow')
     configurations = [project.configurations.shadowed]
     relocate 'org.bouncycastle', 'io.approov.internal.bouncycastle'