Update Grpc.Net.Client for fix

[rwkarg]

Fix unobserved exception from failed calls
grpc/grpc-dotnet#1660

Fixes #
Design discussion issue #

Changes

Updates Grpc.Net.Client to pick up bug fix for unobserved task exceptions.

Merge requirement checklist

• CONTRIBUTING guidelines followed (nullable enabled, static analysis, etc.)
• [-] Unit tests added/updated
• [-] Appropriate CHANGELOG.md files updated for non-trivial changes
• [-] Changes in public API reviewed (if applicable)

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