remove flow in pre-commit hook

.github/CONTRIBUTING.md

@@ -65,7 +65,7 @@ If you are on a Unix-like system, optionally install the Git pre-commit hook wit
 $ npm run install:hooks
 ```
 
-This will run Flow and ESLint on changed files before each commit.
+This will run ESLint on changed files before each commit.
 
 ### Commonly used NPM scripts
 

build/git-hooks/pre-commit

@@ -3,5 +3,5 @@
 files_to_lint=$(git diff --cached --name-only --diff-filter=ACM | grep '\.js$')
 
 if [ -n "$files_to_lint" ]; then
-  flow && NODE_ENV=production eslint $files_to_lint
+  NODE_ENV=production eslint $files_to_lint
 fi