Bump idna from 2.6 to 3.7

Bumps [idna](https://github.com/kjd/idna) from 2.6 to 3.7.
- [Release notes](https://github.com/kjd/idna/releases)
- [Changelog](https://github.com/kjd/idna/blob/master/HISTORY.rst)
- [Commits](https://github.com/kjd/idna/compare/v2.6...v3.7)

---
updated-dependencies:
- dependency-name: idna
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

Pipfile.lock

@@ -3,19 +3,6 @@
         "hash": {
             "sha256": "1e4f55ca8224cc9dd96a096a373c6f73c7f0eb1bddb24fd7faf22093ebe6231b"
         },
-        "host-environment-markers": {
-            "implementation_name": "cpython",
-            "implementation_version": "3.6.3",
-            "os_name": "posix",
-            "platform_machine": "x86_64",
-            "platform_python_implementation": "CPython",
-            "platform_release": "4.13.0-21-generic",
-            "platform_system": "Linux",
-            "platform_version": "#24-Ubuntu SMP Mon Dec 18 17:29:16 UTC 2017",
-            "python_full_version": "3.6.3",
-            "python_version": "3.6",
-            "sys_platform": "linux"
-        },
         "pipfile-spec": 6,
         "requires": {},
         "sources": [
@@ -65,10 +52,12 @@
         },
         "idna": {
             "hashes": [
-                "sha256:8c7309c718f94b3a625cb648ace320157ad16ff131ae0af362c9f21b80ef6ec4",
-                "sha256:2c6a5de3089009e3da7c5dde64a141dbc8551d5b7f6cf4ed7c2568d0cc520a8f"
+                "sha256:028ff3aadf0609c1fd278d8ea3089299412a7a8b9bd005dd08b9f8285bcb5cfc",
+                "sha256:82fee1fc78add43492d3a1898bfa6d8a904cc97d8427f683ed8e798d07761aa0"
             ],
-            "version": "==2.6"
+            "index": "pypi",
+            "markers": "python_version >= '3.5'",
+            "version": "==3.7"
         },
         "imagesize": {
             "hashes": [