Package linux binaries (in Releases) as `tgz` instead of `zip`

[ppenguin]

Is your feature request related to a problem? Please describe.

When using internal CD pipelines to deploy promtail to constrained systems with no unzip available, the workflow for deploying the promtail binary (preferably directly, without intermediate files) is needlessly and significantly complicated by having the archives in a "non-native" format.

Describe the solution you'd like
Use the standard archive formats for respective OS targets (i.e. tar.gz (tgz) on linux).
As a bonus the binaries (in the archives) should have the x bit set, so be mode 0550 or 0750.

Describe alternatives you've considered

Re-archiving on deployment host on-the-fly, but this is impractical since there is no simple one-line-pipe/one-step alternative for zip to tgz conversion without further dependecies.