chore(deps): update prom/prometheus docker digest to 3b1d5be (open-telemetry#726)

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

Author: renovate[bot]

prometheus/docker-compose.yml

@@ -5,7 +5,7 @@ services:
     ports:
       - '19090:19090'
   prometheus:
-    image: prom/prometheus@sha256:9abc6cf6aea7710d163dbb28d8eeb7dc5baef01e38fa4cd146a406dd9f07f70d
+    image: prom/prometheus@sha256:3b1d5be5c3eef4f027665ddaa3b1a7de8a58d96a0a6de5dd45629afd267ecaf0
     volumes:
       - ./prometheus.yml:/etc/prometheus/prometheus.yml
     depends_on: