Add the Rails tests to the pre-commit hook

I'm gonna work on adding modeling tests, and I want to not be breaking
them without realizing! The trade history ones are good to be checking
more often like this, too.

.husky/pre-commit

@@ -1,4 +1,4 @@
 #!/usr/bin/env sh
 . "$(dirname -- "$0")/_/husky.sh"
 
-yarn lint --max-warnings=0 --fix
+yarn lint --max-warnings=0 --fix && bin/rails test