Bump versions.eisopVersion in /docs/examples/errorprone

Bumps `versions.eisopVersion` from 3.42.0-eisop1 to 3.42.0-eisop4.

Updates `io.github.eisop:checker-qual` from 3.42.0-eisop1 to 3.42.0-eisop4
- [Release notes](https://github.com/eisop/checker-framework/releases)
- [Changelog](https://github.com/eisop/checker-framework/blob/master/docs/CHANGELOG.md)
- [Commits](checker-framework-3.42.0-eisop1...checker-framework-3.42.0-eisop4)

Updates `io.github.eisop:checker` from 3.42.0-eisop1 to 3.42.0-eisop4
- [Release notes](https://github.com/eisop/checker-framework/releases)
- [Changelog](https://github.com/eisop/checker-framework/blob/master/docs/CHANGELOG.md)
- [Commits](checker-framework-3.42.0-eisop1...checker-framework-3.42.0-eisop4)

---
updated-dependencies:
- dependency-name: io.github.eisop:checker-qual
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: io.github.eisop:checker
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

docs/examples/errorprone/build.gradle

@@ -11,7 +11,7 @@ plugins {
 
 ext {
     versions = [
-        eisopVersion: '3.42.0-eisop1',
+        eisopVersion: '3.42.0-eisop4',
     ]
 }