chore(deps): update docker.io/library/rockylinux docker tag to v9

Dockerfile.rockylinux8

@@ -12,11 +12,12 @@ RUN dnf update --assumeyes && \
 
 # We must change python to 3.12 (default 3.6), to be compliant with ansible-core. Furthermore, we must upgrade pip to
 # latest version. Otherwise is still used pip for python 3.6. At least, we install boto3, which is required for the aws
-# dynamic inventory manually, because the official python-boto3 package is for python 3.6.
+# dynamic inventory manually, because the official python-boto3 package is for python 3.6. At least, we install
+# ansible-lint via pip to be able to lint ansible roles.
 RUN alternatives --set python3 /usr/bin/python3.12 && \
     curl --fail --silent --location https://bootstrap.pypa.io/get-pip.py --output get-pip.py && \
     python3 get-pip.py && \
-    pip install boto3
+    pip install ansible-lint boto3
 
 # Create default ansible inventory file
 RUN mkdir --parents /etc/ansible