README.md Coloring

This makes the 'Purpur API maven dependency' and 'Purpur API gradle dependency' have coloring. This really isnt
an important change, but compared to Papers README they look devoid of all life and they were sucking away my
remaining will to live :P

README.md

@@ -52,7 +52,7 @@ for the license of material used/modified by this project.
 ## API
 
 Purpur API maven dependency:
-```
+```xml
 <dependency>
     <groupId>net.pl3x.purpur</groupId>
     <artifactId>purpur-api</artifactId>
@@ -60,7 +60,7 @@ Purpur API maven dependency:
     <scope>provided</scope>
 </dependency>
 ```
-```
+```xml
 <repository>
     <id>purpur</id>
     <url>https://repo.pl3x.net/</url>
@@ -68,13 +68,13 @@ Purpur API maven dependency:
 ```
 
 Purpur API gradle dependency:
-```
+```groovy
 maven {
     name 'purpur'
     url 'https://repo.pl3x.net/'
 }
 ```
-```
+```groovy
 compileOnly 'net.pl3x.purpur:purpur-api:1.16.4-R0.1-SNAPSHOT'
 ```