[Dependencies] Update checksum for DCV on Ubuntu20

DCV released some new packages with the same version number. We upgraded the checksum for other operating systems with #2679. After the PR was merged, DCV released new packages for Ubuntu20 too. So we have to update the checksum too.
The checksum is retrieved from https://download.nice-dcv.com/

Signed-off-by: Hanwen <hanwenli@amazon.com>

Author: hanwen-cluster

cookbooks/aws-parallelcluster-platform/resources/dcv/dcv_ubuntu20.rb

@@ -21,5 +21,5 @@
 
 def dcv_sha256sum
   # Ubuntu20 supports DCV on x86
-  '22dcd3c561981794d5170e3002dc9ea7c13ba290c7ed0e2ea910d06b31db3de6'
+  '5151ad6b589dc573e2e067aed0389913e9ecd50bec81935b12e4f952ef14cc56'
 end