fix openapi spec import for specific urls

[Udhay-Adithya]

PR Description

The OpenAPI import feature was failing when trying to import specifications from URLs like https://catfact.ninja/docs?api-docs.json. The error "The fetched content does not look like a valid OpenAPI spec (JSON or YAML)" was shown even though the content was a valid OpenAPI 3.0 specification. This was caused by a bug in the openapi_spec package (v0.15.0) that cannot parse OpenAPI specs containing "security": [[]] (empty security arrays), which is valid according to the OpenAPI 3.0 specification.

Related Issues

• Closes #

Checklist

• I have gone through the contributing guide
• I have updated my branch and synced it with project main branch before making this PR
• I am using the latest Flutter stable branch (run flutter upgrade and verify)
• I have run the tests (flutter test) and all tests are passing

Added/updated tests?

• Yes
• No, and this is why: please replace this line with details on why tests have not been included

OS on which you have developed and tested the feature?

• Windows
• macOS
• Linux

[Udhay-Adithya]

Added a workaround in OpenApiImportService.tryParseSpec() that detects parsing failures and automatically removes problematic security fields containing empty arrays before retrying the parse operation. This is a temporary workaround until the upstream package is fixed.

[animator]

@Udhay-Adithya Can you add links to more real world openAPI spec URLs for which our parser works or doesn't works?