Bump eclipsecbi/fedora-gtk3-mutter in /container

Bumps eclipsecbi/fedora-gtk3-mutter from `321ce3c` to `cc50cbf`.

---
updated-dependencies:
- dependency-name: eclipsecbi/fedora-gtk3-mutter
  dependency-type: direct:production
...

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

container/Dockerfile

@@ -1,4 +1,4 @@
-FROM eclipsecbi/fedora-gtk3-mutter:39-gtk3.24@sha256:321ce3c97bad9e94727eeabb06efbfde9cb77a1b15646235343b1a84d51eba92
+FROM eclipsecbi/fedora-gtk3-mutter:39-gtk3.24@sha256:cc50cbf3a9a26401b58fd069cfe6c1e79dd0be9fd3b5f92c90d7670c5bab81f3
 
 # Back to root for install
 USER 0