fix(ci): drop dead ethjsonrpc extra, install rlp directly

ethjsonrpc package no longer exists on PyPI. Tests don't use it —
only rlp is needed for Ethereum test signing. Install base deps +
rlp directly instead of the stale [ethereum] extra.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: BitHighlander

.github/workflows/ci.yml

@@ -71,8 +71,8 @@ jobs:
       - name: Install dependencies
         run: |
           pip install --upgrade pip
-          pip install -e ".[ethereum]"
-          pip install pytest semver
+          pip install -e .
+          pip install pytest semver rlp
 
       - name: Wait for emulator
         run: |