Duo version update (#104)

For certificate pinning and Verify push
Verified Duo Push for Duo Unix:
https://duo.com/docs/duounix

DigiCert CA bundle expiry article:
https://help.duo.com/s/article/9451?language=en_US

Author: richgerrard

Dockerfile

@@ -12,7 +12,7 @@ RUN apk --update add --virtual .build-deps build-base automake autoconf libtool
 ##
 FROM builder AS duo-builder
 
-ARG DUO_VERSION=2.0.4
+ARG DUO_VERSION=2.2.3
 RUN wget https://dl.duosecurity.com/duo_unix-${DUO_VERSION}.tar.gz && \
     mkdir -p src && \
     tar -zxf duo_unix-${DUO_VERSION}.tar.gz --strip-components=1 -C src