chore(deps) Update dependency Flask to v3

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
Flask (changelog)	^2.0.1 -> ^3.0.0

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[renovate]

⚠ Artifact update problem

Renovate failed to update an artifact related to this branch. You probably do not want to merge this PR as-is.

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• any of the package files in this branch needs updating, or
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The artifact failure details are included below:

File name: poetry.lock

Updating dependencies
Resolving dependencies...


Because no versions of flask-session2 match >1.2.0,<1.3.0 || >1.3.0,<1.3.1 || >1.3.1,<2.0.0
 and flask-session2 (1.2.0) depends on Flask (>=2.2.2,<3.0.0), flask-session2 (>=1.2.0,<1.3.0 || >1.3.0,<1.3.1 || >1.3.1,<2.0.0) requires Flask (>=2.2.2,<3.0.0).
And because flask-session2 (1.3.0) depends on Flask (>=2.2.2,<3.0.0)
 and flask-session2 (1.3.1) depends on Flask (>=2.2.2,<3.0.0), flask-session2 (>=1.2.0,<2.0.0) requires Flask (>=2.2.2,<3.0.0).
So, because atlas-hub depends on both Flask (^3.0.0) and flask-session2 (^1.2.0), version solving failed.