changed version name to 0.3.0

[goekaykaraahmetli]

Purpose

Describe the feature or solved problems

Pre-merge TODOs and Checks

• (exclude checks that are not relevant for your feature)
• PGN file loads correctly
• Navigating through the move history works
• Starting the engine shows moves (test for both sides)
• Selecting a different variant loads a new board with the variant and you can make moves on the board
• In Crazyhouse the pocket pieces are shown and you can drop pieces