feat: add version-file input (#556)

Resolves the GoReleaser version from a file. Currently supports the
asdf/mise `.tool-versions` format; resolved value takes precedence
over the `version` input.

  # .tool-versions
  goreleaser 2.13.0

  - uses: goreleaser/goreleaser-action@v7
    with:
      version-file: .tool-versions
      args: release --clean

Path is resolved relative to `workdir` unless absolute. Bare semvers
are auto-prefixed with `v`; constraint expressions and `latest` are
returned as-is. Multiple fallback versions per asdf convention are
accepted but only the first is used.

Refs #541
Closes #542

Co-authored-by: Anthony Couvreur <22034450+acouvreur@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/context.ts

@@ -7,6 +7,7 @@ export const osArch: string = os.arch();
 export interface Inputs {
   distribution: string;
   version: string;
+  versionFile: string;
   args: string;
   workdir: string;
   installOnly: boolean;
@@ -16,6 +17,7 @@ export async function getInputs(): Promise<Inputs> {
   return {
     distribution: core.getInput('distribution') || 'goreleaser',
     version: core.getInput('version') || '~> v2',
+    versionFile: core.getInput('version-file'),
     args: core.getInput('args'),
     workdir: core.getInput('workdir') || '.',
     installOnly: core.getBooleanInput('install-only')