Bump debian from 11.5-slim to 11.6-slim in /.ci/docker-ci/debian-gnupg1 (#965)

Bumps debian from 11.5-slim to 11.6-slim.

---
updated-dependencies:
- dependency-name: debian
  dependency-type: direct:production
...

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.ci/docker-ci/debian-gnupg1/Dockerfile

@@ -1,4 +1,4 @@
-FROM debian:11.5-slim
+FROM debian:11.6-slim
 
 LABEL maintainer="mail@sobolevn.me"
 LABEL vendor="git-secret team"