epic: v0.21 compatibility for Python SDK

[Unique-Divine]

Context

Make a stable, compatible version of the Python SDK for a v0.21 Nibiru blockchain.

Tasks

• deps: Publish nibiru_proto for v0.21 pre-release #226
• feat!: Update Python SDK and get tests passing for v0.21. #228
• Publish pre-release of the Python SDK for v0.21 nibiru #229
• Import the new pre-release version of nibiru in the examples code. #230
• ci: Make the pricefeeder in the test workflow or configurable from a script. #231
• docs: Update the README and other developer docs if they have deprecations. #232
• Make nibiru_proto a subpackage of the Python SDK.
• The nibiru_proto subpackage must expose its version.
• Use degit when cloning for the proto generation instead of go get to guarantee the buf dependencies are populated. #264

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Related

• release: Publish a GitHub release for the latest version compatible version with a v0.19 Nibiru Chain #233
• feat: Update to v0.21 #251