fix(ci): revert build command from -scheme TabataGo to -target TabataGo

xcodegen 2.45.4 does not generate a "TabataGo" scheme (only
RevenueCatUI, RevenueCatUITests, TabataGoUITests). The -scheme flag
therefore fails. Reverting to -target TabataGo as was previously used.

Verified: all .accessoryCorner usages in TabataGoComplication.swift are
properly guarded with #if canImport(WatchKit), so the watch target
transitive dependency build will not surface accessoryCorner issues.

.gitea/workflows/pr-iphone-deploy.yml

@@ -57,7 +57,7 @@ jobs:
           xcodebuild -list
           xcodebuild build \
             -project TabataGo.xcodeproj \
-            -scheme TabataGo \
+            -target TabataGo \
             -destination "generic/platform=iOS" \
             -configuration Debug \
             -allowProvisioningUpdates \