Avoid ppa for opam too

.github/workflows/main.yml

@@ -148,9 +148,10 @@ jobs:
       - name: Install dependencies
         run: |
           set -ex
-          sudo add-apt-repository ppa:avsm/ppa -y # provides OPAM 2
           sudo apt-get update -qqy
-          sudo apt-get install -qqy ocaml-nox opam libpcre2-dev zlib1g-dev libgtk2.0-dev libmbedtls-dev ninja-build
+          sudo apt-get install -qqy ocaml-nox libpcre2-dev zlib1g-dev libgtk2.0-dev libmbedtls-dev ninja-build
+          curl -sSL https://github.com/ocaml/opam/releases/download/2.3.0/opam-2.3.0-x86_64-linux -o $RUNNER_TEMP/opam
+          sudo install $RUNNER_TEMP/opam /usr/local/bin/opam
 
       - name: Install OCaml libraries
         if: steps.cache-opam.outputs.cache-hit != 'true'

extra/github-actions/workflows/main.yml

@@ -49,9 +49,10 @@ jobs:
       - name: Install dependencies
         run: |
           set -ex
-          sudo add-apt-repository ppa:avsm/ppa -y # provides OPAM 2
           sudo apt-get update -qqy
-          sudo apt-get install -qqy ocaml-nox opam libpcre2-dev zlib1g-dev libgtk2.0-dev libmbedtls-dev ninja-build
+          sudo apt-get install -qqy ocaml-nox libpcre2-dev zlib1g-dev libgtk2.0-dev libmbedtls-dev ninja-build
+          curl -sSL https://github.com/ocaml/opam/releases/download/2.3.0/opam-2.3.0-x86_64-linux -o $RUNNER_TEMP/opam
+          sudo install $RUNNER_TEMP/opam /usr/local/bin/opam
 
       - name: Install OCaml libraries
         if: steps.cache-opam.outputs.cache-hit != 'true'