#190: Add --without-hashes options to poetry export cmd

- This commit also adds the "tests" session to the list of Nox sessions

noxfile.py

@@ -3,7 +3,7 @@
 import nox
 
 # Separating Black away from the rest of the sessions
-nox.options.sessions = "lint", "safety"
+nox.options.sessions = "lint", "safety", "tests"
 code_locations = "datagateway_api", "test", "util", "noxfile.py"
 
 
@@ -14,6 +14,7 @@ def install_with_constraints(session, req_dir=None, *args, **kwargs):
             "export",
             "--dev",
             "--format=requirements.txt",
+            "--without-hashes",
             f"--output={requirements.name}",
             external=True,
         )