testkit: Update NodeJS version in the Dockerfile

The support for the `NodeJS 8.x` was dropped and the `npm update` was failing because of that.
The NodeJS updagrade is being done to `10.x` since it's the oldest version in maintenance.
This update was done by updating the Ubuntu version since the other of updates was broken the TLS configuration. Along with this, the TLS 1.0 was enable in the OpenSSL config since it's disable by default in this ubuntu's version.

Author: bigmontz

testkit/Dockerfile

@@ -1,19 +1,31 @@
-FROM ubuntu:18.04
+FROM ubuntu:20.04
+
+ENV DEBIAN_FRONTEND noninteractive
 
 RUN apt-get update && \
     apt-get install -y \
         git \
         curl \
         python3 \
-        firefox \
         nodejs \
-        npm \
+        npm \ 
+        firefox \
     && rm -rf /var/lib/apt/lists/*
 
 RUN npm install -g npm \
     && /bin/bash -c 'hash -d npm'
 RUN npm install -g gulp
 
+# Enable tls v1.0
+RUN echo "openssl_conf = openssl_configuration\n"|cat - /etc/ssl/openssl.cnf > /tmp/openssl_conf.cnf \  
+    && mv /tmp/openssl_conf.cnf /etc/ssl/openssl.cnf  
+RUN echo "[openssl_configuration]\n\
+ssl_conf = ssl_configuration\n\
+[ssl_configuration]\n\
+system_default = tls_system_default\n\
+[tls_system_default]\n\
+CipherString = DEFAULT:@SECLEVEL=1" >> /etc/ssl/openssl.cnf 
+
 # Install our own CAs on the image.
 # Assumes Linux Debian based image.
 COPY CAs/* /usr/local/share/ca-certificates/