deps: bump fabric-loom from 1.7-SNAPSHOT to 1.8.0-alpha.6

Bumps fabric-loom from 1.7-SNAPSHOT to 1.8.0-alpha.6.

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

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

build.gradle

@@ -2,7 +2,7 @@ import org.apache.tools.ant.filters.ReplaceTokens
 
 plugins {
     id 'org.cadixdev.licenser' version '0.6.1' apply false
-    id 'fabric-loom' version '1.7-SNAPSHOT' apply false
+    id 'fabric-loom' version '1.8.0-alpha.6' apply false
     id 'io.github.goooler.shadow' version '8.1.8'
     id 'org.ajoberstar.grgit' version '5.2.2'
     id 'maven-publish'

fabric-1.20.1/build.gradle

@@ -1,5 +1,5 @@
 plugins {
-    id 'fabric-loom' version '1.7-SNAPSHOT'
+    id 'fabric-loom' version '1.8.0-alpha.6'
     id 'java-library'
     id 'maven-publish'
 }

fabric-1.21/build.gradle

@@ -1,5 +1,5 @@
 plugins {
-    id 'fabric-loom' version '1.7-SNAPSHOT'
+    id 'fabric-loom' version '1.8.0-alpha.6'
     id 'java-library'
     id 'maven-publish'
 }