src: set GOWORK to "off" for macOS builds

Explicitly set GOWORK to "off" when building macOS from source to
ensure we do not pick up go.work files from host repositories where the
action is being run.

Updates https://github.com/tailscale/github-action/issues/287

Signed-off-by: Mario Minardi <mario@tailscale.com>

dist/index.js

@@ -52652,6 +52652,7 @@ async function installTailscaleMacOS(config, toolPath) {
             env: {
                 ...process.env,
                 TS_USE_TOOLCHAIN: "1",
+                GOWORK: "off",
             },
             logMode: config.logMode,
         });

src/main.ts

@@ -696,6 +696,7 @@ async function installTailscaleMacOS(
         env: {
           ...process.env,
           TS_USE_TOOLCHAIN: "1",
+          GOWORK: "off",
         },
         logMode: config.logMode,
       },