Remove patch (not used by deps)

[michaelsproul]

I accidentally left in my patch for ethereum_ssz, but this was unused by v0.12.x releases published to crates.io:

Cargo only looks at the patch settings in the Cargo.toml manifest at the root of the workspace. Patch settings defined in dependencies will be ignored.

https://doc.rust-lang.org/cargo/reference/overriding-dependencies.html#the-patch-section

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 59.25%. Comparing base (bf024bf) to head (59ab260).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #66   +/-   ##
=======================================
  Coverage   59.25%   59.25%           
=======================================
  Files           8        8           
  Lines         297      297           
=======================================
  Hits          176      176           
  Misses        121      121           

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