chore: add 'gpg' package to Docker images (#1004)

Author: mxschmitt

utils/docker/Dockerfile.focal

@@ -10,7 +10,9 @@ RUN apt-get update && \
     # Install utilities required for downloading browsers
     curl \
     # Install utilities required for downloading driver
-    unzip && \
+    unzip \
+    # For the MSEdge install script
+    gpg && \
     rm -rf /var/lib/apt/lists/* && \
     # Create the pwuser
     adduser pwuser