qgis: Add gdal-framework, matplotlib Cask dependencies

[jawshooah]

Per discussion in #8492.

[tapeinosyne]

Sorry, I need to revert this. We cannot remove the caveat until depends_on :cask functionality is available in the stable release.

@jawshooah, your work is appreciated. I had mistakenly assumed that we would not receive external contributions during New Year, and failed to advertise that depends_on :cask stanzas would need to be held until release.

[jawshooah]

Ah, my apologies. I figured that these changes would be included in the first stable release to feature the new functionality.

[tapeinosyne]

Unfortunately that is not the case, which can be confusing: Casks (i.e. the definition files) are updated independently of the actual brew cask command functionality.

[vitorgalvao]

Apologies for my haste in merging these, @ndr-qef; it didn’t cross my mind to check if the changes were already deployed. Shouldn’t sshfs.rb be reverted as well?

[tapeinosyne]

Not to worry; I was largely absent after #8491 and neglected to provide adequate explanation of the follow-ups.

The patch to sshfs needs not be reverted: depends_on :cask has been present in the DSL for quite a while. However, because the stanza will be inoperative until the next release, caveats must include instructions to manually install dependencies.