drop Swift support prior to 5.10

Author: mattpolzin

.github/workflows/tests.yml

@@ -13,10 +13,6 @@ jobs:
       fail-fast: false
       matrix:
         image:
-          - swift:5.8-focal
-          - swift:5.8-jammy
-          - swift:5.9-focal
-          - swift:5.9-jammy
           - swift:5.10-focal
           - swift:5.10-jammy
           - swift:6.0-focal

README.md

@@ -1,4 +1,4 @@
-[![sswg:sandbox|94x20](https://img.shields.io/badge/sswg-sandbox-lightgrey.svg)](https://github.com/swift-server/sswg/blob/master/process/incubation.md#sandbox-level) [![Swift 5.8+](http://img.shields.io/badge/Swift-5.8+-blue.svg)](https://swift.org)
+[![sswg:sandbox|94x20](https://img.shields.io/badge/sswg-sandbox-lightgrey.svg)](https://github.com/swift-server/sswg/blob/master/process/incubation.md#sandbox-level) [![Swift 5.10+](http://img.shields.io/badge/Swift-5.10+-blue.svg)](https://swift.org)
 
 [![MIT license](http://img.shields.io/badge/license-MIT-lightgrey.svg)](http://opensource.org/licenses/MIT) ![Tests](https://github.com/mattpolzin/OpenAPIKit/workflows/Tests/badge.svg)