Upgrade the project to use Xcode 26.4 (and the 26.4 simulator for tests). (#5375)

* Upgrade the project to use Xcode 26.4 (and iOS 26.4 when running tests).

* Update the test OS assertions.

* updated preview tests

# Conflicts:
#	PreviewTests/Sources/__Snapshots__/PreviewTests/homeScreenInviteCell.iPhone-en-GB-0.png
#	PreviewTests/Sources/__Snapshots__/PreviewTests/homeScreenInviteCell.iPhone-pseudo-0.png

* update compound preview tests

---------

Co-authored-by: Mauro Romito <mauro.romito@element.io>

.github/workflows/compound-ios.yml

@@ -36,7 +36,7 @@ jobs:
         persist-credentials: false
 
     - name: Configure Xcode 26
-      run: sudo xcode-select -s /Applications/Xcode_26.1.1.app
+      run: sudo xcode-select -s /Applications/Xcode_26.4.app
         
     - name: Install sourcery
       run: brew install sourcery
@@ -50,7 +50,7 @@ jobs:
 
     - name: Run tests
       working-directory: compound-ios
-      run: set -o pipefail && xcodebuild test -scheme 'Compound' -sdk iphonesimulator -destination 'platform=iOS Simulator,name=Snapshots,OS=26.1' -skipPackagePluginValidation -resultBundlePath Logs/CompoundTests.xcresult | xcbeautify --renderer github-actions
+      run: set -o pipefail && xcodebuild test -scheme 'Compound' -sdk iphonesimulator -destination 'platform=iOS Simulator,name=Snapshots,OS=26.4' -skipPackagePluginValidation -resultBundlePath Logs/CompoundTests.xcresult | xcbeautify --renderer github-actions
 
     - name: Zip artifacts
       if: failure() # We only care about artefacts if the tests fail