Add support for more platform (crazy-max/ghaction-docker-buildx#223)

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

src/context.ts

@@ -2,6 +2,7 @@ import * as os from 'os';
 import * as core from '@actions/core';
 
 export const osPlat: string = os.platform();
+export const osArch: string = os.arch();
 
 export interface Inputs {
   version: string;