Several updated & modernizing codebase

[mzcydev]

This pull request introduces several updates to improve dependencies, enhance code quality, and modernize the codebase. The key changes include transitioning from Bukkit to Spigot dependencies, replacing deprecated libraries, refactoring the RSA key handling logic, and minor documentation updates.

Dependency Updates:

• Updated pom.xml to replace the Bukkit repository and dependency with the Spigot repository and API (spigot-repo with version 1.8.8-R0.1-SNAPSHOT). This modernizes the project and aligns it with newer Minecraft plugin development standards.

Code Modernization:

• Refactored RSAIO.java to use java.util.Base64 instead of the deprecated javax.xml.bind.DatatypeConverter for encoding and decoding. Also, introduced try-with-resources for file handling to improve resource management.

Documentation and Metadata:

• Updated the plugin.yml file to add mzcy_ as an author, reflecting contributions to the project.
• Fixed minor grammatical issues in comments within Votifier.java to improve clarity. [1] [2]

Code Cleanup:

• Removed the outdated GPL license header from RSAIO.java to streamline the file and focus on the functional code.