chore: replace alpine by distroless

Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.15.0
+FROM gcr.io/distroless/static
 ARG TARGETOS
 ARG TARGETARCH
 COPY bin/external-secrets-${TARGETOS}-${TARGETARCH} /bin/external-secrets

e2e/Dockerfile

@@ -10,7 +10,7 @@ RUN wget -q https://storage.googleapis.com/kubernetes-release/release/${KUBECTL_
     wget -q https://get.helm.sh/helm-${HELM_VERSION}-linux-amd64.tar.gz -O - | tar -xzO linux-amd64/helm > /usr/local/bin/helm && \
     chmod +x /usr/local/bin/helm
 
-FROM alpine:3.14.2
+FROM alpine:3.15.0
 RUN apk add -U --no-cache \
     ca-certificates \
     bash \