fix(action.yml): stop evaluating secrets context in input description

[ezequiellich44-cmd]

Every /coinpay run against this action fails at load time on all repos using profullstack/coinpaybot@v0:

##[error]profullstack/coinpaybot/v0/action.yml (Line: 9, Col: 18): Unrecognized named-value: 'secrets'. Located at position 1 within expression: secrets.GITHUB_TOKEN

Why

The github-token input description embeds a real expression: Usually {{ secrets.GITHUB_TOKEN }}. (single-braces in the source). GitHub Actions evaluates {{ }} sequences inside an action's input description when loading the action, and the secrets context is not available there (only inputs, github, env, vars) - so the whole action fails to load and no /coinpay invoice is ever created.

Fix

Replace the literal expression with plain text (the GITHUB_TOKEN secret.). Only the metadata string changes; runtime logic untouched, dist/index.js unchanged.

Impact

Unblocks every CoinPayPortal invoice command repo-wide - e.g. profullstack/malware-test-prs runs #11-#16 all fail from this single line.

[ezequiellich44-cmd]

Status update: 11 merged test-case PRs now pending payout (#170-#180), and every /coinpay run still fails at 'Set up job' because of this single line. The fix is a one-line removal of the invalid default -- no behavior change, just makes the action loadable. Please merge so the queued payments can go through.