Work around a pyftpdlib version incompatibility on Rocky8 by blocking 2.x

versions.

Author: jonasbardino

Dockerfile.rocky8

@@ -817,9 +817,10 @@ RUN if [ "${WITH_PY3}" = "True" ]; then \
 
 # Modules required by grid_ftps
 # NOTE: relies on pyOpenSSL and Cryptography from yum/dnf for now
+# NOTE: python-3.6 fails with unsupported OpenSSL attribute in pyftpdlib-2.x
 RUN pip2 install 'pyftpdlib<2.0'
 RUN if [ "${WITH_PY3}" = "True" ]; then \
-      pip3 install pyftpdlib; \
+      pip3 install 'pyftpdlib<2.0'; \
     fi;
 
 # Modules required by grid_X IO daemons (not available in yum/dnf for python3)