Pipenv: reinstall Pipfile.lock

Pyparsing was updated to 2.4.1 in 5d0139045f
but this version was removed from pip, see
https://github.com/pyparsing/pyparsing/issues/105, so the install failed.

This commit removes Pipfile.lock, reruns `pipenv install`, which updates
the package back to 2.4.0, which is currently the newest version.

Pipfile.lock

@@ -380,7 +380,6 @@
         },
         "pbkdf2": {
             "hashes": [
-                "sha256:90cc5ec6fd99e47f76956093c7dc393923df9afdd89079603b7c944a507338b4",
                 "sha256:ac6397369f128212c43064a2b4878038dab78dab41875364554aaf2a684e6979"
             ],
             "version": "==1.3"
@@ -476,8 +475,7 @@
         },
         "pycparser": {
             "hashes": [
-                "sha256:a988718abfad80b6b157acce7bf130a30876d27603738ac39f140993246b25b3",
-                "sha256:b58b29fc91c9badede7b4d1c05f76887bb54cfd14b449c88a8a075d66901c686"
+                "sha256:a988718abfad80b6b157acce7bf130a30876d27603738ac39f140993246b25b3"
             ],
             "version": "==2.19"
         },
@@ -490,10 +488,10 @@
         },
         "pyparsing": {
             "hashes": [
-                "sha256:530d8bf8cc93a34019d08142593cf4d78a05c890da8cf87ffa3120af53772238",
-                "sha256:f78e99616b6f1a4745c0580e170251ef1bbafc0d0513e270c4bd281bf29d2800"
+                "sha256:1873c03321fc118f4e9746baf201ff990ceb915f433f23b395f5580d1840cb2a",
+                "sha256:9b6323ef4ab914af344ba97510e966d64ba91055d6b9afa6b30799340e89cc03"
             ],
-            "version": "==2.4.1"
+            "version": "==2.4.0"
         },
         "pytest": {
             "hashes": [