Upgrade to Java 17

[pdinklag]

MinecraftStats thus far supported Minecraft 1.13 or later. This means that the highest possible Java version that can be used is Java 8, which is very old (as is 1.13). The result of a recent Discord poll tells me that Minecraft servers using version 1.19 are very rare, and nobody voted for 1.18 or earlier. Minecraft 1.19 requires Java 17, and so it should be safe to upgrade MinecraftStats to Java 17.

Using a newer Java will by no means mean that Minecraft 1.13 is no longer supported. However, the machine that runs MinecraftStats must have Java 17 or later installed.