chore(deps): update ghcr.io/open-feature/sync-testbed docker tag to v0.5.20 (#1139)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

libs/providers/flagd/docker-compose.yaml

@@ -8,7 +8,7 @@ services:
     ports:
       - 8014:8013
   flagd-sync:
-    image: ghcr.io/open-feature/sync-testbed:v0.5.13
+    image: ghcr.io/open-feature/sync-testbed:v0.5.20
     ports:
       - 9090:9090
   flagd-sync-unstable: