Upgrade pulumi-go-provider (#268)

Fixes https://github.com/pulumi/pulumi-docker-build/issues/262.

@iwahbe I realized while putting this together that the provider config
case wasn't actually tested e2e, and I'm skeptical it was ever actually
working. I think it would be reasonable to pull in
https://github.com/pulumi/pulumi-docker-build/pull/253 IMO.

examples/tests/config/index.ts

@@ -0,0 +1,5 @@
+import * as buildx from "@pulumi/docker-build";
+
+new buildx.Provider("with-structured-config", {
+  registries: [{ username: "foo", password: "bar", address: "docker.io" }],
+});