Revert upgrade of pyasn1

Version 0.5.0 of pyasn1 breaks compatiblity with pysnmp (which is
expected) and pysnmplib (which is definitely not expected).

For more information please look at:
- https://github.com/pyasn1/pyasn1/issues/28
- https://github.com/ralphje/signify/issues/37

Change-Id: Ibd7a04c79aa710f98b1c781551464036ced4817f

upper-constraints.txt

@@ -436,7 +436,7 @@ stevedore===5.0.0
 pywinrm===0.4.3
 botocore===1.29.118
 xmltodict===0.13.0
-pyasn1===0.5.0
+pyasn1===0.4.8
 directord===0.12.0
 oslo.rootwrap===7.0.1
 Django===3.2.18