The CentOS 7 openssl11 package is currently not supported. It places files in non-standard locations and uses the non-standard names for pkg-config modules (e.g. openssl11.pc).
Update
You could patch the configure script and force it to use openssl11 module:
sed -i 's/PKG_CONFIG openssl /PKG_CONFIG openssl11 /g' configure
yum install -y epel
yum install -y yum-utils make openssl11-devel
yum-builddep -y python3