Bump cargo-pgrx to 0.11.3 to resolve compile error on aarch64.

[sdier]

Hi, this bumps cargo-pgrx to 0.11.3 to resolve a compilation error on aarch64 -- https://github.com/pgcentralfoundation/pgrx/issues/1429 .

It also migrates some code to a new api in the 0.11.x series for the pg_sys::NodeTag* entities.

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[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
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