Prepare for 1.7.6 release (#885)

Author: brnnmrls

Diff for: AppAuth.podspec

@@ -1,7 +1,7 @@
 Pod::Spec.new do |s|
 
   s.name         = "AppAuth"
-  s.version      = "1.7.5"
+  s.version      = "1.7.6"
   s.summary      = "AppAuth for iOS and macOS is a client SDK for communicating with OAuth 2.0 and OpenID Connect providers."
 
   s.description  = <<-DESC

Diff for: CHANGELOG.md

@@ -1,3 +1,7 @@
+# 1.7.6
+- Fix OIDExternalUserAgentIOSCustomBrowser on versions iOS 10+ ([#871](https://github.com/openid/AppAuth-iOS/pull/871))
+- Update runners in tests.yml to macos-13. ([#886](https://github.com/openid/AppAuth-iOS/pull/886))
+
 # 1.7.5
 - Use correct xcconfig syntax for podspec ([#851](https://github.com/openid/AppAuth-iOS/pull/851))