Bump fabric-loom from 1.7-SNAPSHOT to 1.8.0-alpha.19

Bumps fabric-loom from 1.7-SNAPSHOT to 1.8.0-alpha.19.

---
updated-dependencies:
- dependency-name: fabric-loom
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

build.gradle

@@ -1,6 +1,6 @@
 plugins {
 	// https://fabricmc.net/wiki/documentation:fabric_loom
-	id 'fabric-loom' version '1.7-SNAPSHOT' apply false
+	id 'fabric-loom' version '1.8.0-alpha.19' apply false
     id "org.jetbrains.gradle.plugin.idea-ext" version "1.1.7"
 }