Remove unused/deprecated dependencies, include recent GHCs/stack lts in CI config

[jhrcek]

Hello :slightly_smiling_face: I'd like to use this package to implement SSO in my app. But first, I'd like to get some reasonable assurance this package will keep working with more recent GHC versions. I made the CI green with stack/cabal for all ghc versions from 8.10.7 - 9.8.2 - (see a PR in my fork)

While making the example work with more recent dependencies I also noticed there are few unused dependencies, which can be removed.

I also did some extra-deps shuffling to make sure the examples also work with more recent stack lts resolvers.

[jhrcek]

I think it will be best to get rid of scotty-cookie, because more recent versions of scotty have cookie functionality built in. Marking this as a draft until I implement that simplification..

[jhrcek]

Ready for review. It got rid of scotty-cookie in the examples, because the package has been deprecated some time ago. Instead the cookie functionality is provided by scotty itselt. But that requires using relatively new version of scotty to work, so I bumped the lower bound of scotty in cabal file, which makes it relatively harder to build the examples with older stack resolvers (too many extra-deps required).

Rather than adding too many extra-deps for older stack resolvers just to make the examples work with stack, I decided to disable building examples with stack resolvers < lts-20. Let me know if you're ok with this tradeoff.