update redis exporter image (sourcegraph#1642)

Author: davejrt

base/redis/redis-cache.Deployment.yaml

@@ -49,7 +49,7 @@ spec:
         volumeMounts:
         - mountPath: /redis-data
           name: redis-data
-      - image: index.docker.io/sourcegraph/redis_exporter:18-02-07_bb60087_v0.15.0@sha256:282d59b2692cca68da128a4e28d368ced3d17945cd1d273d3ee7ba719d77b753
+      - image: index.docker.io/sourcegraph/redis_exporter:84464_2021-01-15_c2e4c28@sha256:f3f51453e4261734f08579fe9c812c66ee443626690091401674be4fb724da70
         terminationMessagePolicy: FallbackToLogsOnError
         name: redis-exporter
         ports:

base/redis/redis-store.Deployment.yaml

@@ -49,7 +49,7 @@ spec:
         volumeMounts:
         - mountPath: /redis-data
           name: redis-data
-      - image: index.docker.io/sourcegraph/redis_exporter:18-02-07_bb60087_v0.15.0@sha256:282d59b2692cca68da128a4e28d368ced3d17945cd1d273d3ee7ba719d77b753
+      - image: index.docker.io/sourcegraph/redis_exporter:84464_2021-01-15_c2e4c28@sha256:f3f51453e4261734f08579fe9c812c66ee443626690091401674be4fb724da70
         terminationMessagePolicy: FallbackToLogsOnError
         name: redis-exporter
         ports: