fix:fixing polygon testnet details (#882)

* fix:fixing polygon testnet details

* fix:fixing to typescript network configuration

* Update python/coinbase-agentkit/coinbase_agentkit/network/chain_definitions.py

Co-authored-by: phdargen <pdargent@icloud.com>

* chore: add changelog entry

* Fixed mumbai reference

* Updated the changeset

* Fixed changelog

* Update typescript/.changeset/neat-tables-sort.md

Co-authored-by: phdargen <pdargent@icloud.com>

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Co-authored-by: phdargen <pdargent@icloud.com>