Fix iOS demo app package resolution on CI (pytorch#14952)

Configure Git to use HTTP/1.1 to avoid SPM clone issues.
pytorch#14824

Author: shoumikhin

.ci/scripts/test_ios_ci.sh

@@ -36,6 +36,7 @@ say() {
 
 say "Cloning the Demo App"
 
+git config --global http.postBuffer 524288000
 git clone --depth 1 https://github.com/meta-pytorch/executorch-examples.git
 
 say "Installing CoreML Backend Requirements"