Upgrade ray[serve] to version 1.5.0, allowing kfserving to be installed on python3.9

[Lewiky]

What this PR does / why we need it:

kfserving currently cannot be installed on python versions >3.7 due to a hard dependency on ray[serve]==1.3.0 which itself requires python==3.7.

This PR updates the pinned ray version to 1.5.0 which does support newer python versions, and makes the necessary API changes.

Which issue(s) this PR fixes:
Fixes #1753

Special notes for your reviewer:

1. Please confirm that if this PR changes any image versions, then that's the sole change this PR makes.

Release note:

Adds python3.9 support to KFServing.

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[aws-kf-ci-bot]

Hi @Lewiky. Thanks for your PR.

I'm waiting for a kubeflow member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[yuzisun]

/ok-to-test

[yuzisun]

Thanks @Lewiky !

/lgtm
/approve

[google-oss-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Lewiky, yuzisun

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• python/kfserving/OWNERS [yuzisun]

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[yuzisun]

/lgtm