fix: exclude staging dir from source tarball to prevent self-referencing tar error

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Co-authored-by: ThisIs-Developer <109382325+ThisIs-Developer@users.noreply.github.com>

Author: Copilot

.github/workflows/desktop-build.yml

@@ -63,6 +63,7 @@ jobs:
             --exclude='desktop-app/bin' \
             --exclude='desktop-app/node_modules' \
             --exclude='desktop-app/output' \
+            --exclude="desktop-app/$STAGING" \
             --exclude='.git' \
             desktop-app/
           cd desktop-app