chore: bump dex-controller v0.15.1

[SandhyaRavi2403]

What type of PR is this?
chore

What this PR does/ why we need it:
update the dex-controller to v0.15.1

Which issue(s) this PR fixes:

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

Checklist

• If a chart is changed, the chart version is correctly incremented.
• The commit message explains the changes and why are needed.
• The code builds and passes lint/style checks locally.
• The relevant subset of integration tests pass locally.
• The core changes are covered by tests.
• The documentation is updated where needed.

[SandhyaRavi2403]

@mhrabovcin, the lint is failing ✖︎ dex => (version: "2.13.12", path: "stable/dex") > chart version not ok. Needs a version bump!
The chart version seems to be 2.13.12 which is already bumped. https://artifacthub.io/packages/helm/mesosphere-stable/dex/2.13.12

[mhrabovcin]

@SandhyaRavi2403 you will need to bump the chart version to 2.13.13