[Submodule]: Update sonic-restapi (#10257)

#### Why I did it
```
Update submodule sonic-restapi
bd97dfe Fix urllib3 CVE-2021-33503 issue (#104)
f159bfa Upgrade the containers to be based on Debian Buster (#103)
a1830c1 (origin/201911) Fix OpenAPI spec to be readable by autorest (#101)
```