SPM: unsafe build flags

[weakfl]

Describe your environment

• Xcode version: 12.1
• Firebase SDK version: 7.0.0
• Installation method: Swift Package Manager
• Firebase Component: Core

Describe the problem

After switching from the 7.0-spm-beta branch to version 7.0.0, package loading fails with the target 'gRPC-Core' in product 'gRPC-cpp' contains unsafe build flags. Reverting to the beta branch resolves the issue.

Steps to reproduce:

Switch from beta branch to 7.0.0 version and try to build.

[paulb777]

@weakfl I suspect something in the Xcode state is stale. In Xcode do, File -> Swift Packages -> Reset Package Caches.

The issue you're describing was resolved before the 7.0.0 tag with #6860 and firebase/grpc-SwiftPM@91b6261

[weakfl]

Worked, thanks @paulb777