chore(deps): bump androidx.test.ext:junit in /tutorials/java/Polygons

Bumps androidx.test.ext:junit from 1.2.1 to 1.3.0.

---
updated-dependencies:
- dependency-name: androidx.test.ext:junit
  dependency-version: 1.3.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

tutorials/java/Polygons/gradle/libs.versions.toml

@@ -8,7 +8,7 @@ appcompat = "1.7.1"
 playServicesMaps = "19.2.0"
 kotlinBom = "2.2.0"
 junit = "4.13.2"
-androidxTestExtJunit = "1.2.1"
+androidxTestExtJunit = "1.3.0"
 espressoCore = "3.6.1"
 agp = "8.10.1"