install solc on demand, add coverage to setupy

.github/workflows/test.yml

@@ -51,7 +51,7 @@ jobs:
           pushd tests/e2e/compilation/test_data/test_node_modules/
           npm install hardhat
           popd
-          pytest tests/e2e/compilation/
+          pytest --cov=slither --cov-append tests/e2e/compilation/
           python -m coverage report
 
       - name: unit / core, slithir, utils 

setup.py

@@ -30,6 +30,7 @@ setup(
             "numpy",
             "openai",
             "pdoc",
+            "coverage[toml]",
         ],
     },
     license="AGPL-3.0",

tests/unit/slithir/test_ssa_generation.py

@@ -247,6 +247,7 @@ def select_solc_version(version: Optional[str]) -> None:
         )
         ver = list(vers)[-1]
         version = ".".join(map(str, ver))
+    solc_select.install_artifacts([version])
     env = dict(os.environ)
     env_restore = dict(env)
     env["SOLC_VERSION"] = version