Fix GitHub workflows for real GitHub

[stefanb2]

There is a difference between act-cli and real GitHub environment: context variables contain paths that are not valid inside the runner environment.

Also add git to dependencies to make sure we use a git checkout instead of a tarball.

• add ca-certificates & git packages to dependencies
• move checkout step after dependency installation
• replace ${{ github.workspace }} with ${GITHUB_WORKSPACE} inside steps
• replace ${{ runner.temp }} with ${RUNNER_TEMP} inside steps

[stefanb2]

GitHub guys, WTF?

GITHUB_WORKSPACE=/__w/qMasterPassword/qMasterPassword
RUNNER_WORKSPACE=/__w/qMasterPassword
....
PWD1=/__w/qMasterPassword/qMasterPassword
PWD2=/__w/qMasterPassword/qMasterPassword

# echo "WORKSPACE=${{ github.workspace }}"
WORKSPACE=/home/runner/work/qMasterPassword/qMasterPassword
ls: cannot access '/home/runner/work/qMasterPassword/qMasterPassword': No such file or directory
ls: cannot access '/home/runner/work/qMasterPassword/qMasterPassword/data/icons/': No such file or directory

A documented context value that doesn't work inside the step?

[stefanb2]

@bkueng ready for merging. Let's see if AppImage artifacts appear on the project page after merging this.

[stefanb2]

The uploaded artifacts are hiding on the PR merge build summary page.

Only problem is that GitHub creates a .zip for the download, which is (a) unnecessary as the AppImage is already compressed and (b) does not set the execute flag on the AppImage file, i.e. the user has to manually set after unzipping the contents. This seems to be long-standing issue with artifact up/download, which hopefully will be solved at some point.