Bump ai.elimu:appstore from 2.5.4 to 2.5.15

Bumps ai.elimu:appstore from 2.5.4 to 2.5.15.

---
updated-dependencies:
- dependency-name: ai.elimu:appstore
  dependency-version: 2.5.15
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

gradle/libs.versions.toml

@@ -1,5 +1,5 @@
 [versions]
-elimuAppstore = "2.5.4"
+elimuAppstore = "2.5.15"
 commonsIo = "2.19.0"
 agp = "8.6.0"
 material = "1.12.0"