update fsspec to 2021.06.0 (#7869)

Author: awaelchli

requirements.txt

@@ -5,7 +5,7 @@ torch>=1.4
 future>=0.17.1  # required for builtins in setup.py
 tqdm>=4.41.0
 PyYAML>=5.1,<=5.4.1
-fsspec[http]>=2021.4.0
+fsspec[http]>=2021.05.0, !=2021.06.0
 tensorboard>=2.2.0, !=2.5.0  # 2.5.0 GPU CI error: 'Couldn't build proto file into descriptor pool!'
 torchmetrics>=0.2.0
 pyDeprecate==0.3.0