Align UID with GitHub Actions user

As mentioned in renovatebot#646, we're receiving permissions issues due to the use
of the wrong UID for our user binding.

Closes renovatebot#646.

src/renovate.ts

@@ -17,7 +17,7 @@ class Renovate {
   }
 
   async runDockerContainer(): Promise<void> {
-    const renovateDockerUser = '1000';
+    const renovateDockerUser = '1001';
 
     const dockerArguments = this.input
       .toEnvironmentVariables()