Bump alpine from 3.21.0 to 3.21.1

Bumps alpine from 3.21.0 to 3.21.1.

---
updated-dependencies:
- dependency-name: alpine
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.21.0
+FROM alpine:3.21.1
 WORKDIR /spice/out
 
 ENV TERM="xterm-256color"