update git version

Dockerfile

@@ -17,7 +17,7 @@ RUN set -x \
            && chmod 440 /etc/openvpn/keys/*.crt \
            && yum install -y https://repo.ius.io/ius-release-el7.rpm \
                https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm \
-           && yum install -y git224 \
+           && yum install -y git236 \
            && yum clean all \
            && rm -rf /var/cache/yum