Bump fsspec from 2021.6.0 to 2021.6.1

Bumps [fsspec](https://github.com/intake/filesystem_spec) from 2021.6.0 to 2021.6.1.
- [Release notes](https://github.com/intake/filesystem_spec/releases)
- [Commits](fsspec/filesystem_spec@2021.06.0...2021.06.1)

---
updated-dependencies:
- dependency-name: fsspec
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements_dev_optional.txt

@@ -18,5 +18,5 @@ pytest-cov==2.12.1
 pytest-doctestplus==0.9.0
 h5py==3.2.1
 s3fs==2021.6.0
-fsspec==2021.6.0
+fsspec==2021.6.1
 moto[server]>=1.3.14