ci: fix PowerShell .tar validation

[Richard Markiewicz (thenextman)]

We saw that a .tar archive was corrupted with the warning "There are data after the archive [sic]". This seems like something transient, but validation didn't catch it.

tar -t {path} will not work as expected (at least on Windows); it's needed to pass f to specify the file path. Otherwise tar falls back on \\.\tape0)(!).

Regardless, when validating tar does not set a non-zero error code for this kind of issue.

Instead, use 7z -t which properly sets the error code and allows us to bail out.

[github-actions]

Let maintainers know that an action is required on their side

• Add the label release-required Please cut a new release (Devolutions Gateway, Devolutions Agent, Jetsocat, PowerShell module) when you request a maintainer to cut a new release (Devolutions Gateway, Devolutions Agent, Jetsocat, PowerShell module)

• Add the label release-blocker Follow-up is required before cutting a new release if a follow-up is required before cutting a new release

• Add the label publish-required Please publish libraries (`Devolutions.Gateway.Utils`, OpenAPI clients, etc) when you request a maintainer to publish libraries (Devolutions.Gateway.Utils, OpenAPI clients, etc.)

• Add the label publish-blocker Follow-up is required before publishing libraries if a follow-up is required before publishing libraries