FSPT-119: remove unused bundling dependencies

We don't use these dependencies for pre-processing or bundling css/ js,
lets remove them until they're needed.

This repository seems to manually copy over CSS files during the build
step - this commit doesn't have an opinion on if thats good or bad but
lets only add flask assets back in when its done properly.

pyproject.toml

@@ -7,20 +7,16 @@ license = "MIT License"
 
 requires-python = "~=3.10.0"
 dependencies = [
-    "cssmin==0.2.0",
     "email-validator==2.1.1",
-    "flask-assets==2.0",
     "flask-babel==2.0.0",
     "flask-compress==1.14",
     "flask-talisman==1.1.0",
     "flask-wtf==1.2.1",
     "flask==2.3.3",
     "funding-service-design-utils[toggles]==5.2.0",
     "govuk-frontend-jinja==2.7.0",
-    "jsmin==3.0.1",
     "python-slugify==8.0.4",
     "requests==2.32.3",
-    "pyscss==1.4.0",
 ]
 
 [tool.djlint]