Merge pull request #505 from external-secrets/dependabot/docker/alpine-3.15.0

Bump alpine from 3.14.3 to 3.15.0

Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.14.3
+FROM alpine:3.15.0
 ARG TARGETOS
 ARG TARGETARCH
 COPY bin/external-secrets-${TARGETOS}-${TARGETARCH} /bin/external-secrets