fix(ci): use --set-string for image tags (avoids float coercion of all-digit SHAs)

.woodpecker/backend.yaml

@@ -59,7 +59,7 @@ steps:
           if helm upgrade marktvogt ./helm/marktvogt/ \
               --namespace tenant-2 \
               --reuse-values \
-              --set backend.image.tag="${CI_COMMIT_SHA:0:8}" \
+              --set-string backend.image.tag="${CI_COMMIT_SHA:0:8}" \
               --rollback-on-failure \
               --wait=watcher \
               --timeout 5m

.woodpecker/web.yaml

@@ -66,7 +66,7 @@ steps:
           if helm upgrade marktvogt ./helm/marktvogt/ \
               --namespace tenant-2 \
               --reuse-values \
-              --set web.image.tag="${CI_COMMIT_SHA:0:8}" \
+              --set-string web.image.tag="${CI_COMMIT_SHA:0:8}" \
               --rollback-on-failure \
               --wait=watcher \
               --timeout 5m