Parse schema version when processing saleor webhook

[krzysztofzuraw]

Fix wrong logic introduced in 0.49.0: there is not header saleor-schema-version when app-sdk is processing saleor webhook. This header is only present on install request.

Now app-sdk will try to parse version from version field on GraphQL subscription Event. If field is not present null will be returned.

[changeset-bot]

🦋 Changeset detected

Latest commit: 9e3d0cc

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@saleor/app-sdk	Minor

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[github-actions]

Released snapshot build with @dev tag in npm with version: 0.49.1

Install it with

pnpm add @saleor/app-sdk@0.49.1

[github-actions]

Released snapshot build with @dev tag in npm with version: 0.0.0-pr-20240228150605

Install it with

pnpm add @saleor/app-sdk@0.0.0-pr-20240228150605

[github-actions]

Released snapshot build with @dev tag in npm with version: 0.0.0-pr-20240229095552

Install it with

pnpm add @saleor/app-sdk@0.0.0-pr-20240229095552

[github-actions]

Package	Line Rate	Branch Rate	Complexity	Health
src	79%	93%	0	✔
src.APL	85%	85%	0	✔
src.APL.saleor-cloud	75%	86%	0	✔
src.APL.vercel-kv	54%	69%	0	➖
src.app-bridge	88%	86%	0	✔
src.handlers.next	90%	85%	0	✔
src.handlers.next.saleor-webhooks	94%	80%	0	✔
src.middleware	60%	97%	0	➖
src.settings-manager	96%	89%	0	✔
src.test-utils	100%	90%	0	✔
src.util	82%	100%	0	✔
Summary	83% (3815 / 4581)	87% (453 / 522)	0	✔