change image for pandoc

.drone.yml

@@ -16,7 +16,7 @@ steps:
   - git submodule update --recursive --remote
 
 - name: pandoc
-  image: pandoc/alpine:2.14
+  image: pandoc/core:2.14-alpine
   commands:
     - sh build-pandoc.sh latex user > user-manual.tex
     - sh build-pandoc.sh latex admin > user-manual.tex
@@ -38,10 +38,10 @@ steps:
       - admin-manual.pdf
     checksum:
       - sha512
-    title: ${DRONE_COMMIT_REF}
+    title: ${DRONE_TAG}
     prerelease: true
 ---
 kind: signature
-hmac: 3bfa17ee6ad33613ca8e2fec573050a6d65d3b89e2a0c49f28dbb51b8461a427
+hmac: 96642721ee33af4911e786087ef479b0db15c77b3e32e5e7391397492f3ce180
 
 ...