Update Blastem to latest nightly

[Lutzx]

The version that is currently being used is more than 2 years outdated and it's just another nightly release. I can't even open the System page under Settings and there's tons of issues with controller mapping on this version. These and tons of emulation accuracy fixes have been fixed over the years so I believe using the latest nightly is the best option. The latest nightly also has support for Sega CD emulation. Also fixed some linter errors and warnings that the buildbot found.

[flathubbot]

Started test build 119348

[flathubbot]

Build 119348 successful
To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/102183/com.retrodev.blastem.flatpakref

[flathubbot]

Started test build 119543

[flathubbot]

Build 119543 failed

[flathubbot]

Started test build 119547

[flathubbot]

Build 119547 successful
To test this build, install it from the testing repository:

flatpak install --user https://dl.flathub.org/build-repo/102394/com.retrodev.blastem.flatpakref

[hadess]

I've implemented the linter fixes in #14 and cherry-picked the s/Blastem/BlastEm/ change too. Can you please rebase and squash your changes?