Bump antlr4 from 4.5.3 to 4.9.3 in /modules/lang-painless (#2733)

Bumps [antlr4](https://github.com/antlr/antlr4) from 4.5.3 to 4.9.3.
- [Release notes](https://github.com/antlr/antlr4/releases)
- [Changelog](https://github.com/antlr/antlr4/blob/master/CHANGES.txt)
- [Commits](https://github.com/antlr/antlr4/compare/4.5.3...4.9.3)

---
updated-dependencies:
- dependency-name: org.antlr:antlr4
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

modules/lang-painless/build.gradle

@@ -155,7 +155,7 @@ configurations {
 }
 
 dependencies {
-  regenerate 'org.antlr:antlr4:4.5.3'
+  regenerate 'org.antlr:antlr4:4.9.3'
 }
 
 String grammarPath = 'src/main/antlr'