Upgrade to Gradle 7.6.2

Release 32.1.0 of Guava introduced a number of issues with Gradle metadata:

https://github.com/google/guava/releases/tag/v32.1.0

Upgrading to Gradle 7 avoids having to modify build files to add the
Gradle 6 workarounds for those issues.

Author: jradcliff

google-ads/build.gradle

@@ -28,7 +28,7 @@ import static nl.javadude.gradle.plugins.license.DownloadLicensesExtension.licen
 plugins {
     id 'com.google.api-ads.java-conventions'
     id 'com.google.protobuf' version '0.8.15'
-    id "com.github.hierynomus.license-report" version "0.15.0"
+    id "com.github.hierynomus.license-report" version "0.16.1"
 }
 
 description = 'Google Ads API client library for Java'

gradle/wrapper/gradle-wrapper.jar

@@ -1,5 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-6.9.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.6.2-bin.zip
+networkTimeout=10000
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists