lsb-release: fix reproducibility failure

Make sure help2man output is reproducible. Fixes:

| .\"·DO·NOT·MODIFY·THIS·FILE!··It·was·generated·by·help2man·1.022.	.\"·DO·NOT·MODIFY·THIS·FILE!··It·was·generated·by·help2man·1.022.
| .TH·FSG·"1"·"April·2021"·"FSG·lsb_release·v1.4"·FSG	.TH·FSG·"1"·"May·2021"·"FSG·lsb_release·v1.4"·FSG
| .SH·NAME	3 	.SH·NAME

Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>