Bump github.com/hashicorp/terraform-plugin-go from 0.19.1 to 0.20.0 (#90

)

Bumps [github.com/hashicorp/terraform-plugin-go](https://github.com/hashicorp/terraform-plugin-go) from 0.19.1 to 0.20.0.
- [Release notes](https://github.com/hashicorp/terraform-plugin-go/releases)
- [Changelog](https://github.com/hashicorp/terraform-plugin-go/blob/main/CHANGELOG.md)
- [Commits](hashicorp/terraform-plugin-go@v0.19.1...v0.20.0)

---
updated-dependencies:
- dependency-name: github.com/hashicorp/terraform-plugin-go
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>