Correcting Cadence Web docker image version

[dandowlinghmlr]

Since v3.20.0, cadence web version strings include a v

What kind of change does this PR introduce (Bug fix, feature, docs update, ...)?
Bug Fix

What is the current behavior?
Attempting to pull "docker.io/ubercadence/web:3.35.6" fails

What is the new behavior (if this is a feature change)?
Image pulls correctly with the v

Does this PR introduce a breaking change? If so, what actions will users need to take in order to regain compatibility?
non breaking

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[AShaww]

Good spot!