.github/workflows: Upgrade deprecated macos-11 to macos-latest

See https://github.com/actions/runner-images

.github/workflows/build.yml

@@ -49,7 +49,7 @@ jobs:
             quicktest: true
 
           - job_name: mac_amd64
-            os: macos-11
+            os: macos-latest
             go: '>=1.22.0-rc.1'
             gotags: 'cmount'
             build_flags: '-include "^darwin/amd64" -cgo'
@@ -58,7 +58,7 @@ jobs:
             deploy: true
 
           - job_name: mac_arm64
-            os: macos-11
+            os: macos-latest
             go: '>=1.22.0-rc.1'
             gotags: 'cmount'
             build_flags: '-include "^darwin/arm64" -cgo -macos-arch arm64 -cgo-cflags=-I/usr/local/include -cgo-ldflags=-L/usr/local/lib'
@@ -138,7 +138,7 @@ jobs:
           brew update
           brew install --cask macfuse
           brew install git-annex
-        if: matrix.os == 'macos-11'
+        if: matrix.os == 'macos-latest'
 
       - name: Install Libraries on Windows
         shell: powershell