fix: use version key for master install in zvm

[hendriknielaender]

Overview

This PR introduces a critical update to the Zig Version Manager (zvm) that resolves an issue with the installation of the master version of Zig. Previously, when attempting to install the master version, zvm would not correctly utilize the version key provided in the JSON configuration, leading to installation failures. With this update, zvm now correctly references the version key for master, ensuring that the unique development version of Zig is accurately fetched and installed.

Changes

• Modified fetchVersionData function to use the version key in the JSON configuration when installing the master version.
• Added a conditional check in the installation process to determine whether the master version is requested, and if so, to use the unique version identifier provided by the JSON configuration.
• Implemented additional logging for debugging purposes, providing clear output for each step in the installation process, aiding in future troubleshooting.

Impact

• Users can now install the master version of Zig without encountering the EmptyVersion error.
• The installation process for development versions of Zig is more robust and less likely to fail due to mismatches in expected version identifiers.

Notes

This fix is crucial for developers who rely on the cutting-edge features of Zig and need to work with the latest development builds. The zvm's reliability is significantly improved, promoting a smoother development experience for the Zig community.

Closes #17