[Dependencies] Web3.py upgrade to version 7

[calina-c]

@trizin I noticed the web3.py upgrade is again reverted. I created this ticket to track this better. Please add to this ticket any information on why the upgrades are reverted, when and how they are merged, and let's document some proper testing parameters. I will also use this as a reference ticket when doing upgrades e.g. to close unwarranted dependabot PRs trying to upgrade eth-account or web3.py. My suggestion is to keep this open until we are 100% that an upgrade is in place and it works properly.

History up until now:
1st merge, with web3.py 7.1.0 took place in 30 Aug: 80c68fe
reverted on 1st Sep: e056b4b

2nd attempt, on 3 Sep, using version 7.2.0 which fixed the transact() bug initially present in 7.1.0 and reduced the scope of the changes needed in pdr-backend: 7b83654
reverted on 5 Sep: 4606ac8

[trizin]

One users raised an issue: Starting a predictoor with the latest version fails with the following error:

File "/root/pdr-backend/venv3/pdr-backend/pdr_backend/predictoor/predictoor_agent.py", line 223, in take_step
    self.submit_prediction_txs(
  File "/root/pdr-backend/venv3/lib/python3.11/site-packages/enforce_typing/decorator.py", line 29, in wrapper
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "/root/pdr-backend/venv3/pdr-backend/pdr_backend/predictoor/predictoor_agent.py", line 317, in submit_prediction_txs
    tx = self.pred_submitter_mgr.submit_prediction(
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/root/pdr-backend/venv3/pdr-backend/pdr_backend/contract/pred_submitter_mgr.py", line 100, in submit_prediction
    return self.config.w3.eth.wait_for_transaction_receipt(tx)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/root/pdr-backend/venv3/lib/python3.11/site-packages/web3/eth/eth.py", line 476, in wait_for_transaction_receipt
    tx_receipt = self._transaction_receipt(transaction_hash)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^