fixes the docker publisher, also enables manual triggering (#1331)

Author: ivg

.github/workflows/publish-docker-image.yml

@@ -2,6 +2,7 @@ name: Publish Docker
 on:
   schedule:
     - cron: "0 4 * * *" # Every day at 4:00 a.m. UTC, midnight EDT
+  workflow_dispatch:
 
 jobs:
   build:

docker/ubuntu/bionic/Dockerfile

@@ -2,10 +2,11 @@ FROM ocaml/opam2:ubuntu-18.04
 
 WORKDIR /home/opam
 
-RUN sudo add-apt-repository ppa:ivg/ghidra -y \
+RUN sudo apt-get update  \
+ && sudo apt-get install software-properties-common -y \
+ && sudo add-apt-repository ppa:ivg/ghidra -y \
  && sudo apt-get install libghidra-dev -y \
  && sudo apt-get install libghidra-data -y \
- && sudo apt-get update  \
  && opam switch 4.09 \
  && eval "$(opam env)" \
  && opam remote set-url default https://opam.ocaml.org \