Update executorch release version to 1.2.0 in release_versions.sh (#7911)

Update the executorch version in release_versions.sh to 1.2.0, as per
https://github.com/pytorch/test-infra/wiki/Releasing-to-download.pytorch.org-and-pypi.
Similar change for previous executorch release:
#7697

Author: manuelcandales

release/release_versions.sh

@@ -9,7 +9,7 @@ TORCHCOMMS_VERSION=${TORCHCOMMS_VERSION:-0.2.0}
 TRITON_VERSION=${TRITON_VERSION:-3.3.0}
 TORCHTEXT_VERSION=${TORCHTEXT_VERSION:-0.18.0}
 TORCHREC_VERSION=${TORCHREC_VERSION:-1.5.0}
-EXECUTORCH_VERSION=${EXECUTORCH_VERSION:-1.1.0}
+EXECUTORCH_VERSION=${EXECUTORCH_VERSION:-1.2.0}
 TORCH_TENSORRT_VERSION=${TORCH_TENSORRT_VERSION:-2.11.0}
 TORCH_TENSORRT_RTX_VERSION=${TORCH_TENSORRT_VERSION}
 TORCHAO_VERSION=${TORCHAO_VERSION:-0.17.0}