Update Scylla Manager version to 3.4.0

[rzetelskik]

Description of your changes: This PR updates Scylla Manager version to 3.4.0, which was released today. We should be testing against the most recent release.

Which issue is resolved by this Pull Request:
Resolves #

/kind machinery
/priority important-longterm
/cc

[scylla-operator-bot]

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In response to this:

Description of your changes: This PR updates Scylla Manager version to 3.4.0, which was released today. We should be testing against the most recent release.

Which issue is resolved by this Pull Request:
Resolves #

/kind machinery
/priority important-longterm
/cc

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[rzetelskik]

/cc zimnx tnozicka

[tnozicka]

/approve
/assign zimnx

[zimnx]

/lgtm

[scylla-operator-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: rzetelskik, tnozicka, zimnx

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