no_proxy matching agains parts of the host name is not supported

[gendergap]

It is quite common to define the no_proxy environment variable like this:

NO_PROXY=.part.of.some.domain.com,some-other-host.domain.com

In practice, this matches all contained hosts for many HTTP clients. But for action runners, it does not.
Consider a GitHub host like github.part.of.some.domain.com. I would expect this host to be excluded from the HTTP proxy, but the Actions runner only recognizes this if I put the variable like this:

NO_PROXY=github.part.of.some.domain.com,.part.of.some.domain.com,some-other-host.domain.com

The relevant code is https://github.com/actions/toolkit/blob/main/packages/http-client/src/proxy.ts#L50

Perhaps the no_proxy matching could be broadened a bit?