remove: swift 5.7 and 5.8 support on CI

.github/workflows/builds.yml

@@ -14,13 +14,13 @@ jobs:
     strategy:
       matrix:
         os: [ macos-latest ]
-        swift: ["5.7", "5.8", "5.9", "5.10"]
+        swift: ["5.9", "5.10"]
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v4
       - uses: maxim-lobanov/setup-xcode@v1
         with:
-          xcode-version: '15.2.0'
+          xcode-version: '15.3.0'
       - uses: fwal/setup-swift@v2
         with:
           swift-version: ${{ matrix.swift }}

.github/workflows/nightly.yml

@@ -10,7 +10,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest]
-        swift: ["5.7", "5.8", "5.9", "5.10"]
+        swift: ["5.9", "5.10"]
     runs-on: ${{ matrix.os }}
     steps:
       - uses: actions/checkout@v4

CHANGELOG.md

@@ -4,4 +4,8 @@
 - `Sendable` conformance to `Version` to satisfy build warnings when complete concurrency checks are enabled
 - [SwiftFormat](https://github.com/nicklockwood/SwiftFormat/tree/main) with a format file. lint checks are done on CI
 
+### Removed
+
+- support for swift 5.7 and 5.8 on CI
+
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/), and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).