Makefile, build.gradle: update gradle to 8.13.0 (#828)

updates tailscale/corp#40476

8.6.1 does not support API 36.  8.13.0 is the minimum required
version.

Signed-off-by: Jonathan Nobels <jonathan@tailscale.com>

Makefile

@@ -10,7 +10,7 @@
 # with this name, it will be used.
 #
 # The convention here is tailscale-android-build-amd64-<date>
-DOCKER_IMAGE := tailscale-android-build-amd64-072226-2
+DOCKER_IMAGE := tailscale-android-build-amd64-072226-3
 
 # The integration test image contains the Android emulator, system image, SDK,
 # build-tools, NDK, adb, and helper tools needed to run the emulator-backed Go

android/build.gradle

@@ -11,7 +11,7 @@ buildscript {
         }
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:8.6.1'
+        classpath 'com.android.tools.build:gradle:8.13.0'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
         classpath "org.jetbrains.kotlin:kotlin-serialization:$kotlin_version"
         classpath("com.ncorti.ktfmt.gradle:plugin:0.17.0")

android/gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionSha256Sum=544c35d6bd849ae8a5ed0bcea39ba677dc40f49df7d1835561582da2009b961d
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.7-bin.zip
+distributionSha256Sum=20f1b1176237254a6fc204d8434196fa11a4cfb387567519c61556e8710aed78
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.13-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists