chore(datastore): update PR template with checkpoints

[lawmicha]

Issue #, if available:

Description of changes: Until the integration tests are running consistently successfully in github actions, add a PR template reminder to run the integration tests manually.

Check points: (check or cross out if not relevant)

• [ ] Added new tests to cover change, if needed
• [ ] Build succeeds with all target using Swift Package Manager
• [ ] All unit tests pass
• [ ] All integration tests pass
• [ ] Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)
• [ ] Documentation update for the change if required
• [ ] PR title conforms to conventional commit style
• [ ] If breaking change, documentation/changelog update with migration instructions

DataStore checkpoints (check when completed)

• [ ] Ran AWSDataStorePluginIntegrationTests
• [ ] Ran AWSDataStorePluginV2Tests
• [ ] Ran AWSDataStorePluginMultiAuthTests
• [ ] Ran AWSDataStorePluginCPKTests
• [ ] Ran AWSDataStorePluginAuthCognitoTests
• [ ] Ran AWSDataStorePluginAuthIAMTests

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.