perf: Remove MANIFEST.in

Faster pip install -e erpnext

https://stackoverflow.com/questions/24727709/do-python-projects-need-a-manifest-in-and-what-should-be-in-it

https://github.com/frappe/frappe/pull/7360

MANIFEST.in

@@ -1,20 +0,0 @@
-include MANIFEST.in
-include requirements.txt
-include *.json
-include *.md
-include *.py
-include *.txt
-include .travis.yml
-recursive-include erpnext *.txt
-recursive-include erpnext *.css
-recursive-include erpnext *.csv
-recursive-include erpnext *.html
-recursive-include erpnext *.ico
-recursive-include erpnext *.js
-recursive-include erpnext *.json
-recursive-include erpnext *.md
-recursive-include erpnext *.png
-recursive-include erpnext *.py
-recursive-include erpnext *.svg
-recursive-include erpnext/public *
-recursive-exclude * *.pyc