chore(deps): update module github.com/nats-io/nats.go to v1.15.0

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
github.com/nats-io/nats.go	require	minor	v1.13.1-0.20220308171302-2f2f6968e98d -> v1.15.0

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Release Notes

nats-io/nats.go

### [`v1.15.0`](https://togithub.com/nats-io/nats.go/releases/v1.15.0) [Compare Source](https://togithub.com/nats-io/nats.go/compare/v1.14.0...v1.15.0) ##### Changelog ##### Experimental The `ObjectStore` is still experimental and subject to change. ##### Added - ObjectStore: - `MaxBytes` in the `ObjectStoreConfig` structure ([#​955](https://togithub.com/nats-io/nats.go/issues/955)) ##### Improved - JetStream: - Ability pass `0` to `nats.ExpectLastSequence(0)` and `nats.ExpectLastSequencePerSubject(0)` to the `js.Publish()` call. Previously, the value `0` would be ignored and the header would not be set. Note that currently, the server only accepts `0` as a valid value for `nats.ExpectLastSequencePerSubject()`. Thanks to [@​bruth](https://togithub.com/bruth) for the contribution ([#​958](https://togithub.com/nats-io/nats.go/issues/958)) ##### Fixed - JetStream: - A PullConsumer's Fetch() method with a batch greater than 1 and with other pull consumers running, may timeout although messages would have been available ([#​967](https://togithub.com/nats-io/nats.go/issues/967)) ##### Complete Changes

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