GitHub Actions: Have the build workflow compile the needed Spigot jar

.github/actions/setup_project_workspace/action.yml

@@ -0,0 +1,22 @@
+name: Prepare Workspace
+description: Prepares the workspace for compilation
+
+inputs:
+  maven_username:
+    required: false
+    description: The username to use for the Maven server
+  maven_password:
+    required: false
+    description: The password to use for the Maven server
+
+runs:
+  using: composite
+  steps:
+    - uses: craftaro/GH-Commons/.github/actions/setup_workspace@master
+      with:
+        maven_username: ${{ inputs.maven_username }}
+        maven_password: ${{ inputs.maven_password }}
+
+    - uses: SpraxDev/Action-SpigotMC@v4
+      with:
+        versions: 1.20.1

.github/workflows/build.yml

@@ -23,7 +23,7 @@ jobs:
     steps:
       - uses: actions/checkout@v3
       - name: Prepare Workspace
-        uses: craftaro/GH-Commons/.github/actions/setup_workspace@master
+        uses: ./.github/actions/setup_project_workspace
         with:
           maven_username: ${{ secrets.PLUGINS_MAVEN_REPO_USERNAME }}
           maven_password: ${{ secrets.PLUGINS_MAVEN_REPO_PASSWORD }}