Bump avago 1.12.0

[ceyonur]

This pull request includes several updates to version dependencies and configuration files. The most important changes are the updates to the versions of AVALANCHEGO, subnet-evm, and other dependencies across multiple files.

Version Updates:

• Updated AVALANCHEGO_VERSION from v1.11.13 to v1.12.0 in .devcontainer/devcontainer.json, go.mod, and scripts/versions.sh. [1] [2] [3]
• Updated subnet-evm version from v0.6.12 to v0.7.0 in go.mod and scripts/versions.sh. [1] [2]
• Updated min_go_version from ~1.21.12 to ~1.22.8 in .github/workflows/tests.yml.

Dependency Updates:

• Updated github.com/ava-labs/coreth from v0.13.9-rc.1 to v0.13.9-rc.2-encapsulate-signer in go.mod.
• Updated various golang.org/x dependencies to newer versions in go.mod.

Miscellaneous:

• Added a new version entry v0.3.0 with protocol version 38 in compatibility.json.
• Updated the Version constant to v0.3.0 in plugin/main.go.