Bump websockets from 6.0 to 9.1

Bumps [websockets](https://github.com/aaugustin/websockets) from 6.0 to 9.1.
- [Release notes](https://github.com/aaugustin/websockets/releases)
- [Changelog](https://github.com/aaugustin/websockets/blob/9.1/docs/changelog.rst)
- [Commits](python-websockets/websockets@6.0...9.1)

---
updated-dependencies:
- dependency-name: websockets
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements.txt

@@ -5,7 +5,7 @@ eth_rlp==0.1.2
 numpy==1.19.1
 requests==2.20.0
 pysha3==1.0.2
-websockets==6.0
+websockets==9.1
 eth_hash==0.2.0
 rlp==1.1.0
 tqdm==4.49.0

setup.py

@@ -78,7 +78,7 @@
         "lru-dict>=1.1.6,<2.0.0",
         "eth-hash[pycryptodome]>=0.2.0,<1.0.0",
         "requests>=2.11.0,<3.0.0",
-        "websockets>=6.0.0,<7.0.0",
+        "websockets>=6.0.0,<10.0.0",
         "pypiwin32>=223;platform_system=='Windows'", 'rlp', 'pysha3', 'eth_rlp',
         "attrdict>=2.0.1",
         "parsimonious>=0.8.1"