Update linux workflow and Fix Rakefile (set-output replaced, issue #21)

[Okkoma]

• Removed web platform from Linux workflow (already supported by web workflow).
• Updated Rakefile (replaced deprecated ::set-output).
• Added build type (rel, dbg) in generated artifacts name.
• Updated Linux workflow to v4.

Note: Applying this commit with "linux fixes" commit fixes Linux build for master branch

[klaussilveira]

Thanks for the contribution @Okkoma! The current state of the build definitely needs attention.