Move to GitHub Actions

[probonopd]

Since Travis CI is no longer working, this needs to be moved to GitHub Actions so that we can build again.

This blocks all builds and PRs.

[humble-barnacle001]

@probonopd could you mention the version of qt you used earlier for creating in travis CI so that I can write up an action

Alternatively, could you write up a bash file required for building the AppImage on a local machine so that I could derive an action from it? Current script relies heavily on TravisCI workflow which I am not too familiar about

[probonopd]

Closed in adf1eb0. Thanks @RICCIARDI-Adrien