* Fix serverTrust crash (#4542)

* Update readme, add stale bot, add issue template, add pull request template

* Update copy from Alamofire

* Fix crash on nil serverTrust

* Expose server trust error

* add test for error throws

* Fix nullability

* Fix evaluateServerTrust determination (#4552)

Co-authored-by: Jon Shier <jon@jonshier.com>

* Revert changes making error generation public.

This reverts commit 111352b.

# Conflicts:
#	AFNetworking/AFURLSessionManager.m

* Make static error function a method instead.

* Make trust generatio part of AFTestCase.

* Add test cases for server trust error generation.

* Mark parameters explicitly nullable.

* Fix nullability (#4551)

* Replace instead of appending to the default header (#4550)

* Replace instead of appending to the default header

* Add tests for setting HTTP headers per request

* Fix SPM usage with better publicHeadersPath. (#4554)

Co-authored-by: Jakub Kašpar <kaspikk@gmail.com>
Co-authored-by: Elf Sundae <elf.sundae@gmail.com>