Dockerfile.base: update to alpine:3.15

Signed-off-by: Maisem Ali <[email protected]>

Dockerfile.base

@@ -2,5 +2,5 @@
 # Use of this source code is governed by a BSD-style
 # license that can be found in the LICENSE file.
 
-FROM alpine:3.14
+FROM alpine:3.15
 RUN apk add --no-cache ca-certificates iptables iproute2 ip6tables