[LibOS] test/apps: Add PyTorch example (AlexNet image classification)

.ci/run-pylint

@@ -16,6 +16,7 @@ find . -name \*.py \
     -and -not -path ./LibOS/glibc-\?.\?\?/\* \
     -and -not -path ./LibOS/shim/test/apps/ltp/opt/\* \
     -and -not -path ./LibOS/shim/test/apps/ltp/src/\* \
+    -and -not -path ./LibOS/shim/test/apps/pytorch/\* \
 | sed 's/./\\&/g' \
 | xargs "${PYLINT}" "$@" \
     Pal/src/host/Linux-SGX/signer/pal-sgx-get-token \

LibOS/shim/test/apps

@@ -1 +1 @@
-Subproject commit 9185188e7da27f528a4990c037f488bc0dff2068
+Subproject commit 252170e343d249e3eb2db2c7eaefd47663306792