[MIGraphX EP] [ROCm EP] Update CI to use ROCm 6.4 (#23535)
### Description
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Update Onnxruntime CI to use latest ROCm release ROCm 6.3.2
### Motivation and Context
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- If it fixes an open issue, please link to the issue here. -->
Ensure CI is testing up to date with recent Onnxruntime. AMD validates
changes based off the latest ROCm release and adds additional features
on top to validate changes prior to being pushed to our internal testing
branches and then up streamed to Microsoft/Onnxruntime:main . Right now
Onnxruntime is testing things a few releases back for their CI
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Co-authored-by: Ted Themistokleous <tedthemistokleous@amd.com>
