Bump flake8 from 3.8.4 to 3.9.0 in /dependencies (#1365)

Bumps [flake8](https://gitlab.com/pycqa/flake8) from 3.8.4 to 3.9.0.
- [Release notes](https://gitlab.com/pycqa/flake8/tags)
- [Commits](https://gitlab.com/pycqa/flake8/compare/3.8.4...3.9.0)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

dependencies/Pipfile.lock

@@ -309,11 +309,11 @@
         },
         "flake8": {
             "hashes": [
-                "sha256:749dbbd6bfd0cf1318af27bf97a14e28e5ff548ef8e5b1566ccfb25a11e7c839",
+                "sha256:12d05ab02614b6aee8df7c36b97d1a3b2372761222b19b58621355e82acddcff",
-                "sha256:aadae8761ec651813c24be05c6f7b4680857ef6afaae4651a4eccaef97ce6c3b"
+                "sha256:78873e372b12b093da7b5e5ed302e8ad9e988b38b063b61ad937f26ca58fc5f0"
             ],
             "index": "pypi",
-            "version": "==3.8.4"
+            "version": "==3.9.0"
         },
         "gitdb": {
             "hashes": [
@@ -560,10 +560,10 @@
         },
         "pycodestyle": {
             "hashes": [
-                "sha256:2295e7b2f6b5bd100585ebcb1f616591b652db8a741695b3d8f5d28bdc934367",
+                "sha256:514f76d918fcc0b55c6680472f0a37970994e07bbb80725808c17089be302068",
-                "sha256:c58a7d2815e0e8d7972bf1803331fb0152f867bd89adf8a01dfd55085434192e"
+                "sha256:c389c1d06bf7904078ca03399a4816f974a1d590090fecea0c63ec26ebaf1cef"
             ],
-            "version": "==2.6.0"
+            "version": "==2.7.0"
         },
         "pycparser": {
             "hashes": [
@@ -574,10 +574,10 @@
         },
         "pyflakes": {
             "hashes": [
-                "sha256:0d94e0e05a19e57a99444b6ddcf9a6eb2e5c68d3ca1e98e90707af8152c90a92",
+                "sha256:910208209dcea632721cb58363d0f72913d9e8cf64dc6f8ae2e02a3609aba40d",
-                "sha256:35b2d75ee967ea93b55750aa9edbbf72813e06a66ba54438df2cfac9e3c27fc8"
+                "sha256:e59fd8e750e588358f1b8885e5a4751203a0516e0ee6d34811089ac294c8806f"
             ],
-            "version": "==2.2.0"
+            "version": "==2.3.0"
         },
         "pygments": {
             "hashes": [