Update gcc

Changes:

- https://github.com/docker-library/gcc/commit/5c6a497: Merge pull request https://github.com/docker-library/gcc/pull/112 from infosiftr/15-ga
- https://github.com/docker-library/gcc/commit/a842bfe: Add gcc 15
- https://github.com/docker-library/gcc/commit/4b19a61: Update shebang from /bin/bash to /usr/bin/env bash
- https://github.com/docker-library/gcc/commit/fdd6fce: Simplify and update `verify-templating.yml`
- https://github.com/docker-library/gcc/commit/9498dfd: Update README
- https://github.com/docker-library/gcc/commit/a689008: Update `generate-stackbrew-library.sh` to support `BASHBREW_LIBRARY` for easier cascading updates

library/gcc

@@ -1,11 +1,18 @@
-# this file is generated via https://github.com/docker-library/gcc/blob/6d49ef0aad84aee23d918a9dba54ffc62927d9a9/generate-stackbrew-library.sh
+# this file is generated via https://github.com/docker-library/gcc/blob/a842bfea737b1127a922a27d768df7e382f740af/generate-stackbrew-library.sh
 
 Maintainers: Tianon Gravi <[email protected]> (@tianon),
              Joseph Ferguson <[email protected]> (@yosifkit)
 GitRepo: https://github.com/docker-library/gcc.git
 
+# Last Modified: 2025-04-25
+Tags: 15.1.0, 15.1, 15, latest, 15.1.0-bookworm, 15.1-bookworm, 15-bookworm, bookworm
+Architectures: amd64, arm32v5, arm32v7, arm64v8, ppc64le, s390x
+GitCommit: a842bfea737b1127a922a27d768df7e382f740af
+Directory: 15
+# Docker EOL: 2026-10-25
+
 # Last Modified: 2024-08-01
-Tags: 14.2.0, 14.2, 14, latest, 14.2.0-bookworm, 14.2-bookworm, 14-bookworm, bookworm
+Tags: 14.2.0, 14.2, 14, 14.2.0-bookworm, 14.2-bookworm, 14-bookworm
 Architectures: amd64, arm32v5, arm32v7, arm64v8, ppc64le, s390x
 GitCommit: 22c26a9e4edb4ce4f7676dfa100afc80fc2ccbea
 Directory: 14