fix: Dockerfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-DEBIAN11-GLIBC-5927133
- https://snyk.io/vuln/SNYK-DEBIAN11-GLIBC-5927133
- https://snyk.io/vuln/SNYK-DEBIAN11-NCURSES-2767191
- https://snyk.io/vuln/SNYK-DEBIAN11-NCURSES-2767191
- https://snyk.io/vuln/SNYK-DEBIAN11-NCURSES-5421197

Dockerfile

@@ -13,7 +13,7 @@ COPY . .
 RUN make -j$(nproc) ${RELEASE_TYPE}
 RUN make ci-release
 
-FROM debian:11.6-slim as container
+FROM debian:bullseye-20240423-slim as container
 
 COPY --from=build /lethean/build/packaged/lethean* /usr/local/bin/
 RUN apt-get update && apt-get install -y ca-certificates