Update dependencies and bump version to 0.5.7

Upgraded several dependencies in go.mod and go.sum, including `golang.org/x/net` and `golang.org/x/sync`. Adjusted the version references in the README and main codebase to reflect the new release version 0.5.7.

Update MockFragment Stats method

The changes include synchronizing access to the underlying map when calculating the Length stat in the MockFragment's Stats() method. This is to ensure thread safety while accessing shared resources.

Revert "Update license header"

This reverts commit c213d6b.

fix: panic on start when BindAddr cannot be resolved #217

chore: release Olric v0.5.3

chore: release v0.5.2

chore: release v0.5.1

chore: Update README.md

fix: return nil instead of argument error if there is no listener on …

…a topic. Logging this event is just enough.

chore: upgrade consistent to v0.10.0