[SYNPY-1524] Updates Dockerfile (#1137)

* set python version for ghcr, test build

* uncomment line

* adds for develop

* revert last

* updates dockerfile

* remove whitespace

* remove 3.9 setting

* change to 3.9-slim

.github/workflows/build.yml

@@ -462,9 +462,6 @@ jobs:
     steps:
       - name: Check out the repo
         uses: actions/checkout@v4
-      - uses: actions/setup-python@v5
-        with:
-          python-version: 3.9
       - name: Extract Release Version
         run: echo "RELEASE_VERSION=${GITHUB_REF#refs/tags/}" >> $GITHUB_ENV
         shell: bash
@@ -518,9 +515,6 @@ jobs:
     steps:
       - name: Check out the repo
         uses: actions/checkout@v4
-      - uses: actions/setup-python@v5
-        with:
-          python-version: 3.9
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v2
       - name: Log in to GitHub Container Registry

Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:20.04
+FROM python:3.9-slim
 RUN echo 'debconf debconf/frontend select Noninteractive' | debconf-set-selections
 
 RUN apt-get update \