Upgrade Alpine version for both Dockerfiles

... to improve/mitigate performance problems, see #2299.
(musl libc vs. glibc)

Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine:3.16
+FROM alpine:3.17
 
 RUN apk update && \
     apk upgrade && \

Dockerfile.git

@@ -1,6 +1,6 @@
 # Build using git repo
 
-FROM alpine:3.16
+FROM alpine:3.17
 
 WORKDIR /home/testssl