feat: Add SubscriptionID to EventSubSubscriptionsParams

[arnokay]

related issue: #240

[jackmcguire1]

Update the tests!

[arnokay]

added test for SubscriptionID.
also added test for multiple filter parameters error and expanded comment on EventSubSubscriptionsParams. its regarding the rule in API (link):

Use the status, type, user_id, and subscription_id query parameters to filter the list of subscriptions that are returned. The filters are mutually exclusive; the request fails if you specify more than one filter.

[Copilot]

Pull Request Overview

This PR adds support for filtering EventSub subscriptions by SubscriptionID and clarifies that filter parameters are mutually exclusive.

• Adds a new SubscriptionID field to EventSubSubscriptionsParams struct
• Updates documentation to clarify that filters are mutually exclusive (except After)
• Adds test coverage for both error case (multiple filters) and success case (subscription ID filtering)

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
eventsub.go	Adds SubscriptionID field to filter parameters, updates comment to clarify mutual exclusivity, removes extra blank line
eventsub_test.go	Adds test cases for bad request when multiple filters are specified and successful subscription ID lookup

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[coveralls]

Pull Request Test Coverage Report for Build 19191202170

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.004%) to 92.734%

---

Totals
Change from base Build 14026929583:	-0.004%
Covered Lines:	1723
Relevant Lines:	1858

---

💛 - Coveralls