Switch to flit (#823)

Author: blink1073

.flake8

@@ -0,0 +1,17 @@
+[flake8]
+ignore = E501, W503, E402
+builtins = c, get_config
+exclude =
+    .cache,
+    .github,
+    docs,
+    setup.py
+enable-extensions = G
+extend-ignore =
+    G001, G002, G004, G200, G201, G202,
+    # black adds spaces around ':'
+    E203,
+per-file-ignores =
+    # B011: Do not call assert False since python -O removes these calls
+    # F841 local variable 'foo' is assigned to but never used
+    tests/*: B011, F841

MANIFEST.in

@@ -14,6 +14,8 @@ To create a manual release, perform the following steps:
 pip install tbump twine build
 git pull origin $(git branch --show-current)
 git clean -dffx
+npm install
+npm run build
 ```
 
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