Repoint build stamping at the app-versioning skill's script

Replaces the repo-local Scripts/update_build_number.sh (which git-tagged
on every build) with the shared update_build_info.sh referenced in place
from indie-skills: same commit-count CFBundleVersion and BuildDate, adds
BuildHash, and makes release tagging opt-in via RELEASE_TAGGING=1.
Verified BuildDate/BuildHash/CFBundleVersion land in the built app.

project.yml

@@ -52,8 +52,8 @@ targets:
       - package: Yams
       - target: Workouts Watch App
     postBuildScripts:
-      - script: '"${SRCROOT}/Scripts/update_build_number.sh"'
-        name: Update Build Number
+      - script: '"${SRCROOT}/../indie-skills/skills/app-versioning/scripts/update_build_info.sh"'
+        name: Update Build Info
         shell: /bin/sh
         basedOnDependencyAnalysis: false
         inputFiles:
@@ -89,8 +89,8 @@ targets:
       - target: Workouts Watch Widget
         embed: true
     postBuildScripts:
-      - script: '"${SRCROOT}/Scripts/update_build_number.sh"'
-        name: Update Build Number
+      - script: '"${SRCROOT}/../indie-skills/skills/app-versioning/scripts/update_build_info.sh"'
+        name: Update Build Info
         shell: /bin/sh
         basedOnDependencyAnalysis: false
         inputFiles: