fix(ci): added dynamic verus version detection

[liamjdavis]

This pull request updates the Verus installation process to ensure the correct Rust toolchain is installed automatically, improving reliability and reducing manual maintenance. The workflow now dynamically detects and installs the Rust toolchain required by Verus, and the installation script has improved error handling. It also updates the erdos-graph submodule to a new commit.

CI/CD Workflow Improvements:

• Removed the hardcoded Rust toolchain installation from .github/workflows/ci.yml to avoid mismatches with Verus requirements.
• Added a step in .github/workflows/ci.yml to detect and install the Rust toolchain required by the installed Verus version, ensuring compatibility.

Verus Installation Script Enhancements:

• Improved tools/install-verus.sh to fail fast if the Verus binary is not found, providing clear error messages.
• Modified tools/install-verus.sh to automatically detect and install the Rust toolchain required by Verus, and verify the installation.

Submodule Update:

• Updated the erdos-graph submodule to a new commit, bringing in the latest changes from its repository.