Fix iOS demo app package resolution on CI (#14959)

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

Co-authored-by: Anthony Shoumikhin <anthony@shoumikh.in>

Author: pytorchbot

.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"