pip: use hypothesis==4.38.1 and attrs==18.2.0

to workaround nixos pip/pipenv issue

Pipfile

@@ -57,7 +57,8 @@ typing = "*"
 
 # storage
 cryptography = "*"
-hypothesis = "*"
+hypothesis = "==4.38.1"  # let's use this version because of the nixos pipenv/pip issue
+attrs = "==18.2.0"  # let's use this version because of the nixos pipenv/pip issue
 
 [dev-packages]
 scan-build = "*"

Pipfile.lock

@@ -1,7 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "f3b7bbe143d49aaef753b93c9f08f493b626a66575f535447f4f2cca2187bf97"
+            "sha256": "278da7171f4ada120a583717d3f395251518b381fc56b3c37f05751933661848"
         },
         "pipfile-spec": 6,
         "requires": {},
@@ -30,10 +30,11 @@
         },
         "attrs": {
             "hashes": [
-                "sha256:08a96c641c3a74e44eb59afb61a24f2cb9f4d7188748e76ba4bb5edfa3cb7d1c",
-                "sha256:f7b7ce16570fe9965acd6d30101a28f62fb4a7f9e926b3bbc9b61f8b04247e72"
+                "sha256:10cbf6e27dbce8c30807caf056c8eb50917e0eaafe86347671b57254006c3e69",
+                "sha256:ca4be454458f9dec299268d472aaa5a11f67a4ff70093396e1ceae9c76cf4bbb"
             ],
-            "version": "==19.3.0"
+            "index": "pypi",
+            "version": "==18.2.0"
         },
         "autoflake": {
             "hashes": [
@@ -262,11 +263,11 @@
         },
         "hypothesis": {
             "hashes": [
-                "sha256:6847df3ffb4aa52798621dd007e6b61dbcf2d76c30ba37dc2699720e2c734b7a",
-                "sha256:acd47600deb55e9c2c98de6deef23384160ed0fdaafb6753146e556c077d3c78"
+                "sha256:2d0f5c69d939da4c2d6e1e686623c26a91087f3fc9077cd865013f532583dc05",
+                "sha256:d66286a7a67946d843b37c5656321ea3fd318c259dc0ed9aeb6f2d4b037b876a"
             ],
             "index": "pypi",
-            "version": "==4.41.2"
+            "version": "==4.38.1"
         },
         "idna": {
             "hashes": [