dependabot npm(deps): bump @grpc/grpc-js from 1.8.12 to 1.8.13

Bumps @grpc/grpc-js from 1.8.12 to 1.8.13.

Release notes

Sourced from @​grpc/grpc-js's releases.

@​grpc/grpc-js 1.8.13

• Fix memory leak in channelz socket tracking (#2394)

Commits

• 114c87c Merge pull request #2394 from murgatroid99/grpc-js_transport_leak
• ad719cc Merge pull request #2391 from murgatroid99/grpc-js-xds_node_client_version
• 4fa8af3 Merge pull request #2392 from murgatroid99/grpc-js-xds_tests_1.8.x
• 6b7c99b Merge pull request #2395 from murgatroid99/grpc-js-xds_weighted_target_simple...
• e5e6731 grpc-js-xds: Use simpler search algorithm in weighted target picker
• 3fbdf0d grpc-js: Bump version to 1.8.13
• 056dc8e grpc-js: Unregister socket from channelz when closing transport
• e32bbc7 grpc-js-xds: Allow tests to set bootstrap info in channel args
• 6bc6b86 grpc-js-xds: Add unit test framework
• 481f704 grpc-js-xds: Populate Node message field user_agent_version
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