feat: adjust Drone config

.drone.yml

@@ -1,10 +1,21 @@
+---
 kind: pipeline
 name: default
 
 steps:
-- name: gitea_release
+  - name: build
+    image: sphinxdoc/sphinx-latexpdf:5.0.2
+    commands:
+      - apt-get update
+      - apt-get -y install texlive-lang-german rsync
+      - pip install -r requirements.txt
+      - make -j4 latexpdf
+  - name: gitea_release
     image: plugins/gitea-release
     settings:
-    api_key: xxxxxxxx
+      api_key:
+        from_secret: gitea_token
       base_url: https://git.wtf-eg.de
       files: build/latex/rtfm-dashandbuchderfreefederatedfleetfffleetinitiative.pdf
+    when:
+      event: tag