CI: Test core/views/generic.py (#772)

* Adds tests for GET /wallet

* Update `httpx` to `0.23.0` and `http-core` to `0.15.0` in `venv` installation path

* Fix `secp256k1 = "==0.14.0"` and `cffi = "==1.15.0"`

.github/workflows/regtest.yml

@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [3.7]
+        python-version: [3.8]
     steps:
       - uses: actions/checkout@v2
       - name: Set up Python ${{ matrix.python-version }}
@@ -54,7 +54,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: [3.7]
+        python-version: [3.8]
     steps:
       - uses: actions/checkout@v2
       - name: Set up Python ${{ matrix.python-version }}