Make encoding/yaml.ts type-compatible with Deno Deploy

[kt3k]

Currently yaml can't be used in Deploy because of the following errors:

$ deployctl run test.ts 
Check file:///Users/kt3k/tmp/deploy-test/$deno$eval.ts
error: TS2694 [ERROR]: Namespace 'Deno' has no exported member 'Reader'.
  async readFrom(r: Deno.Reader): Promise<number> {
                         ~~~~~~
    at https://deno.land/std@0.95.0/io/buffer.ts:196:26

TS2694 [ERROR]: Namespace 'Deno' has no exported member 'ReaderSync'.
  readFromSync(r: Deno.ReaderSync): number {
                       ~~~~~~~~~~
    at https://deno.land/std@0.95.0/io/buffer.ts:226:24

Found 2 errors.
error: Process exited with code 1

[wperron]

Maybe we could add Reader and Writer types to Deploy? 🤔

[lucacasonato]

Plan to fix this in denoland/deno#9795