dev env: add upper version constraint for `click` to keep compatibility with python3.5

https://github.com/fphammerle/switchbot-mqtt/commit/cfa4f82e751567445163f3233e9305c0d0086b31

Pipfile

@@ -26,6 +26,8 @@ pytest-cov = ">=2"
 # python3.5 compatibility
 # https://github.com/PyCQA/astroid/commit/d81f07becf3243a84e0baaa3493ce74cafed8022#diff-60f61ab7a8d1910d86d9fda2261620314edcae5894d5aaa236b821c7256badd7R52
 astroid = "<2.5"
+# https://github.com/pallets/click/commit/9374365fdd5af45fc3dc4047963fa30aad9ce15c
+click = "<8"
 # <2 for:
 # > pkg_resources.VersionConflict: (importlib-metadata 2.1.1 (/home/travis/virtualenv/python3.5.10/lib/python3.5/site-packages),
 # > Requirement.parse('importlib-metadata<2,>=0.12; python_version < "3.8"'))

Pipfile.lock

@@ -1,7 +1,7 @@
 {
     "_meta": {
         "hash": {
-            "sha256": "05134b39cf9fa77c9d74b63e4cb1e3ddeb24ebf0cb320f170ea18bf0beaf9a83"
+            "sha256": "3c6252b09754ae955efc58092506bca01ea96a31ac0a614fd542352c07ff5d04"
         },
         "pipfile-spec": 6,
         "requires": {
@@ -130,6 +130,7 @@
                 "sha256:d2b5255c7c6349bc1bd1e59e08cd12acbbd63ce649f2588755783aa94dfb6b1a",
                 "sha256:dacca89f4bfadd5de3d7489b7c8a566eee0d3676333fbb50030263894c38c0dc"
             ],
+            "index": "pypi",
             "version": "==7.1.2"
         },
         "coverage": {