ci: fix Ubuntu deps for secp256k1 build

- Remove libsecp256k1-0 (not available on Ubuntu 24.04).
- Install pkg-config, libsecp256k1-dev, build-essential, python3-dev.

Author: GaloisField2718

.github/workflows/ci.yml

@@ -57,7 +57,7 @@ jobs:
     - name: Install system dependencies (secp256k1 build)
       run: |
         sudo apt-get update
-        sudo apt-get install -y pkg-config libsecp256k1-dev libsecp256k1-0
+        sudo apt-get install -y pkg-config libsecp256k1-dev build-essential python3-dev
     
     - name: Cache pipenv dependencies
       uses: actions/cache@v4