ci: remove macos-11 runner

The macOS 11 runner image was removed on 6/28/2024.
https://github.blog/changelog/2024-05-20-actions-upcoming-changes-to-github-hosted-macos-runners/

Therefore Carthage support was removed from README since the 'carthage' job can
no longer be run and then 'carthage' build can not be checked.

.github/workflows/ci.yml

@@ -36,15 +36,6 @@ jobs:
           - swift: "5.5"
             xcode: "13.2.1"
             runs-on: macos-12
-          - swift: "5.4"
-            xcode: "12.5.1"
-            runs-on: macos-11
-          - swift: "5.3"
-            xcode: "12.4"
-            runs-on: macos-11
-          - swift: "5.2"
-            xcode: "11.7"
-            runs-on: macos-11
     steps:
       - uses: actions/checkout@v4
       - name: Building in Swift ${{ matrix.swift }}
@@ -161,13 +152,6 @@ jobs:
           -Xswiftc "-sdk" -Xswiftc "`xcrun --sdk iphonesimulator --show-sdk-path`" \
           -Xswiftc "-target" -Xswiftc "${{ matrix.target }}"
 
-  carthage:
-    runs-on: macos-11
-    steps:
-    - uses: actions/checkout@v4
-    - name: "Carthage build"
-      run: carthage build --use-xcframeworks --no-skip-current
-
   cocoapods:
     runs-on: macos-14
     env:

README.md

@@ -2,7 +2,6 @@
 [![Platform](https://img.shields.io/cocoapods/p/FloatingPanel.svg)](https://cocoapods.org/pods/FloatingPanel)
 [![Version](https://img.shields.io/cocoapods/v/FloatingPanel.svg)](https://cocoapods.org/pods/FloatingPanel)
 ![GitHub Workflow Status (with branch)](https://img.shields.io/github/actions/workflow/status/scenee/FloatingPanel/ci.yml?branch=master)
-[![Carthage compatible](https://img.shields.io/badge/carthage-compatible-4BC51D.svg?style=flat)](https://github.com/Carthage/Carthage)
 
 # FloatingPanel
 
@@ -22,7 +21,6 @@ Please see also [the API reference@SPI](https://swiftpackageindex.com/scenee/Flo
 - [Requirements](#requirements)
 - [Installation](#installation)
   - [CocoaPods](#cocoapods)
-  - [Carthage](#carthage)
   - [Swift Package Manager](#swift-package-manager)
 - [Getting Started](#getting-started)
   - [Add a floating panel as a child view controller](#add-a-floating-panel-as-a-child-view-controller)
@@ -104,14 +102,6 @@ it, simply add the following line to your Podfile:
 pod 'FloatingPanel'
 ```
 
-### Carthage
-
-For [Carthage](https://github.com/Carthage/Carthage), add the following to your `Cartfile`:
-
-```ogdl
-github "scenee/FloatingPanel"
-```
-
 ### Swift Package Manager
 
 Follow [this doc](https://developer.apple.com/documentation/swift_packages/adding_package_dependencies_to_your_app).