ci: use ubuntu-latest

Author: jmckenna

.github/workflows/build-linux.yml

@@ -17,7 +17,7 @@ jobs:
           run: |
             if [[ 'minimal,default,maximal' =~ ${{ matrix.option }} ]]
             then
-              sudo add-apt-repository -y ppa:ubuntugis/ppa
+              sudo add-apt-repository -y ppa:ubuntugis/ubuntugis-unstable
               sudo apt-get update -y
               sudo apt-get upgrade -y
               sudo apt-get install -y libcurl4-openssl-dev apache2-dev