Bump net.ltgt.errorprone in /docs/examples/errorprone

Bumps net.ltgt.errorprone from 3.1.0 to 4.0.1.

---
updated-dependencies:
- dependency-name: net.ltgt.errorprone
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

docs/examples/errorprone/build.gradle

@@ -4,7 +4,7 @@
 
 plugins {
     id 'java'
-    id 'net.ltgt.errorprone' version '3.1.0'
+    id 'net.ltgt.errorprone' version '4.0.1'
     // Checker Framework pluggable type-checking
     id 'org.checkerframework' version '0.6.40'
 }