Restrict urllib3 v2 as it breaks the build

[medvedev1088]

Fixes the error in Travis CI https://app.travis-ci.com/github/blockchain-etl/ethereum-etl/jobs/603030848

  File "/home/travis/build/blockchain-etl/ethereum-etl/.tox/py39/lib/python3.9/site-packages/web3/__init__.py", line 9, in <module>
    from web3.main import (
  File "/home/travis/build/blockchain-etl/ethereum-etl/.tox/py39/lib/python3.9/site-packages/_pytest/assertion/rewrite.py", line 296, in load_module
    six.exec_(co, mod.__dict__)
  File "/home/travis/build/blockchain-etl/ethereum-etl/.tox/py39/lib/python3.9/site-packages/web3/main.py", line 87, in <module>
    from web3.manager import (
  File "/home/travis/build/blockchain-etl/ethereum-etl/.tox/py39/lib/python3.9/site-packages/_pytest/assertion/rewrite.py", line 296, in load_module
    six.exec_(co, mod.__dict__)
  File "/home/travis/build/blockchain-etl/ethereum-etl/.tox/py39/lib/python3.9/site-packages/web3/manager.py", line 37, in <module>
    from web3.middleware import (
  File "/home/travis/build/blockchain-etl/ethereum-etl/.tox/py39/lib/python3.9/site-packages/web3/middleware/__init__.py", line 35, in <module>
    from .exception_retry_request import (  # noqa: F401
  File "/home/travis/build/blockchain-etl/ethereum-etl/.tox/py39/lib/python3.9/site-packages/_pytest/assertion/rewrite.py", line 296, in load_module
    six.exec_(co, mod.__dict__)
  File "/home/travis/build/blockchain-etl/ethereum-etl/.tox/py39/lib/python3.9/site-packages/web3/middleware/exception_retry_request.py", line 9, in <module>
    from requests.exceptions import (
  File "/home/travis/build/blockchain-etl/ethereum-etl/.tox/py39/lib/python3.9/site-packages/requests/__init__.py", line 43, in <module>
    import urllib3
  File "/home/travis/build/blockchain-etl/ethereum-etl/.tox/py39/lib/python3.9/site-packages/urllib3/__init__.py", line 38, in <module>
    raise ImportError(
ImportError: urllib3 v2.0 only supports OpenSSL 1.1.1+, currently the 'ssl' module is compiled with OpenSSL 1.0.2g  1 Mar 2016. See: https://github.com/urllib3/urllib3/issues/2168
py39: exit 1 (0.90 seconds) /home/travis/build/blockchain-etl/ethereum-etl> pytest pid=4099
.pkg: _exit> python /home/travis/virtualenv/python3.9.6/lib/python3.9/site-packages/pyproject_api/_backend.py True setuptools.build_meta __legacy__
  py39: FAIL code 1 (27.83=setup[26.92]+cmd[0.90] seconds)
  evaluation failed :( (32.71 seconds)

urllib3 v2 requires openssl 1.1.1+ which is not available in xenial image https://urllib3.readthedocs.io/en/stable/v2-migration-guide.html

[medvedev1088]

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