env: downgrade more-itertools to restore compatibility with python3.4

https://travis-ci.org/fphammerle/free-disk/jobs/630904240#L212

Pipfile

@@ -7,6 +7,8 @@ name = "pypi"
 free-disk = {editable = true, path = "."}
 
 [dev-packages]
+# v8.0.0 dropped python3.4 support
+more-itertools = "<8"
 pylint = ">=2.3.0"
 pytest = "*"
 

Pipfile.lock

@@ -1,7 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "cce3f2f618132127134ad38ab756fd1fba8e7b934e9d72f684b51a3786f8a90e"
+            "sha256": "d4b79fc22599a54a52c244bea5819bc07a905d093eb2d6032a3b35042fe0fce4"
         },
         "pipfile-spec": 6,
         "requires": {
@@ -86,10 +86,11 @@
         },
         "more-itertools": {
             "hashes": [
-                "sha256:b84b238cce0d9adad5ed87e745778d20a3f8487d0f0cb8b8a586816c7496458d",
-                "sha256:c833ef592a0324bcc6a60e48440da07645063c453880c9477ceb22490aec1564"
+                "sha256:409cd48d4db7052af495b09dec721011634af3753ae1ef92d2b32f73a745f832",
+                "sha256:92b8c4b06dac4f0611c0729b2f2ede52b2e1bac1ab48f089c7ddc12e26bb60c4"
             ],
-            "version": "==8.0.2"
+            "index": "pypi",
+            "version": "==7.2.0"
         },
         "packaging": {
             "hashes": [