Update to the windows-2022 CI environment

This doesn't have Innosetup installed by default, so that needs to manually installed now

Also, we now manually specify macos-11 to be clear about what image is being used.

.github/workflows/build.yml

@@ -47,7 +47,7 @@ jobs:
         if-no-files-found: error
 
   build-macos:
-    runs-on: macos-latest
+    runs-on: macos-11
 
     steps:
     - uses: actions/checkout@v2
@@ -86,7 +86,7 @@ jobs:
         if-no-files-found: error
 
   build-windows:
-    runs-on: windows-latest
+    runs-on: windows-2022
 
     steps:
     - uses: actions/checkout@v2
@@ -103,6 +103,7 @@ jobs:
     # Note that msgfmt is already available from the Git for Windows installation!
     - name: Build Installer
       run: |
+        choco install innosetup -y -v
         dotnet publish Pinta.sln -p:BuildTranslations=true --configuration Release -r win-x64 --self-contained true
         iscc installer/windows/installer.iss