action.yml: bump gitops-pusher version (#47)

Pick up a fix from tailscale/tailscale#14296

action.yml: bump gitops-pusher version (#47)

Pick up a fix from tailscale/tailscale#14296

Merge pull request #42 from tailscale/irbekrm/bump_deps

README.md,action.yml: bump versions

action: bump version of setup-go action

Most notably, this moves from node16 to node20.

Signed-off-by: Will Norris <will@tailscale.com>

action.yml: recombine gitops-pusher calls

We previously split the gitops-pusher steps based on which auth
variables were set due to a bug in the gitops-pusher tool itself.  That
as fixed in tailscale/tailscale#11025, so we can now recombine these.

Update to latest tagged version of tailscale to pull in the fix, and
bump the go version while we're at it.

Co-authored-by: Mario Minardi <mario@tailscale.com>
Signed-off-by: Will Norris <will@tailscale.com>

Merge pull request #34 from tailscale/mpminardi/oauth-fix

action.yml: add separate steps for API key and OAuth flows

README: add docs for OAuth credentials

Updates #24

Signed-off-by: Will Norris <will@tailscale.com>

Fetch from tag gitops-1.30.0 instead of v1.30.0

Signed-off-by: Denton Gentry <dgentry@tailscale.com>

Initial commit

This is a GitOps action for Tailscale users. This enables users to set
up their Tailscale ACLs in a GitHub repository and then have changes be
pushed out by CI. This also allows changes to be reviewed in CI and have
CI fail if ACL tests fail.

More details to come.

Signed-off-by: Xe <xe@tailscale.com>