fix: update proxy_account_class_hash in .env.example

[bajpai244]

Resolves: #496

Pull Request type

Updates the .env.example with the latest correct class hash for proxy class account.

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Build-related changes
• Documentation content changes
• Testing

What is the new behavior?

The correct class hash has been updated.

Does this introduce a breaking change?

• Yes
• No

[codecov]

Codecov Report

Patch coverage: 83.25% and project coverage change: +49.18% 🎉

Comparison is base (71506a8) 23.17% compared to head (fa438c9) 72.35%.
Report is 193 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #497       +/-   ##
===========================================
+ Coverage   23.17%   72.35%   +49.18%     
===========================================
  Files           9       44       +35     
  Lines        1247     3994     +2747     
===========================================
+ Hits          289     2890     +2601     
- Misses        958     1104      +146     

Files Changed	Coverage Δ
crates/core/src/mock/serde.rs	0.00% <0.00%> (ø)
crates/core/src/models/transaction.rs	93.63% <ø> (ø)
crates/core/src/models/transaction_receipt.rs	97.02% <ø> (ø)
crates/core/src/test_utils/bin/dump-katana.rs	0.00% <ø> (ø)
crates/core/src/test_utils/deploy_helpers.rs	32.44% <ø> (ø)
crates/core/src/test_utils/execution_helpers.rs	100.00% <ø> (ø)
crates/core/src/test_utils/fixtures.rs	100.00% <ø> (ø)
crates/eth-rpc/src/api/alchemy_api.rs	100.00% <ø> (ø)
crates/eth-rpc/src/api/eth_api.rs	100.00% <ø> (ø)
crates/eth-rpc/src/api/net_api.rs	100.00% <ø> (ø)
... and 34 more

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