Update GHC.Dockerfile

- Install package yamllint
- Also install HLint
  - w/o installing haskell-linter extension

.devcontainer/GHC.Dockerfile

@@ -24,6 +24,8 @@ FROM glcr.b-data.ch/commercialhaskell/ssi:${STACK_VERSION_OVERRIDE} as ssi
 
 FROM ${BUILD_ON_IMAGE}${HLS_SFX} as hls
 
+FROM glcr.b-data.ch/ndmitchell/hlsi as hlsi
+
 FROM docker.io/koalaman/shellcheck:stable as sci
 
 FROM ${BUILD_ON_IMAGE}:${GHC_VERSION}
@@ -33,9 +35,9 @@ COPY --from=files /files /
 RUN sysArch="$(uname -m)" \
   ## Ensure that common CA certificates
   ## and OpenSSL libraries are up to date
-  && apk upgrade --no-cache \
-    ca-certificates \
-    openssl-dev \
+  && apk upgrade --no-cache ca-certificates openssl-dev \
+  ## Install yamllint
+  && apk add --no-cache yamllint \
   ## Install hadolint
   && case "$sysArch" in \
     x86_64) tarArch="x86_64" ;; \
@@ -86,8 +88,13 @@ RUN if [ -n "$USE_ZSH_FOR_ROOT" ]; then \
   fi
 
 ## Copy binaries as late as possible to avoid cache busting
+## Install Stack
 COPY --from=ssi /usr/local /usr/local
+## Install HLS
 COPY --from=hls /usr/local /usr/local
+## Install HLint
+COPY --from=hlsi /usr/local /usr/local
+## Install ShellCheck
 COPY --from=sci --chown=root:root /bin/shellcheck /usr/local/bin
 
 ARG HLS_VERSION