Remove parallelisation (#1833)

* Refactor code

* Edit tox

* Modify tox

* Modify tests

* Reduce processes

* Reduce processes

* Remove parallel test

* Remove test

tests/integration_tests/parallel_test.py

@@ -1,16 +0,0 @@
-from subprocess import Popen, PIPE
-from tests import PROJECT_DIR, TESTDATA
-import json
-
-MYTH = str(PROJECT_DIR / "myth")
-
-
-def test_parallel():
-
-    test_file = str(TESTDATA / "input_contracts" / "origin.sol")
-    program = f"python3 {MYTH} a {test_file} --solv 0.5.0 -o json"
-    processes = [Popen(program, stdout=PIPE, shell=True) for i in range(4)]
-    for p in processes:
-        out, err = p.communicate()
-        json_output = json.loads(out.decode("utf-8"))
-        assert json_output["success"] == True