Merge pull request #5061 from ninjarobot/patch-38

Update swipl to 7.7.21

library/swipl

@@ -1,10 +1,10 @@
 Maintainers: Dave Curylo <[email protected]> (@ninjarobot)
 GitRepo: https://github.com/SWI-Prolog/docker-swipl.git
-GitCommit: 599c776108e4cb86002c857dd9deee36f5388778
+GitCommit: 1d06a09d029ed545f01076049408c1dee081d045
 
-Tags: latest, 7.7.20
+Tags: latest, 7.7.21
 Architectures: amd64, arm32v7, arm64v8
-Directory: 7.7.20/stretch
+Directory: 7.7.21/stretch
 
 Tags: stable, 7.6.4
 Directory: 7.6.4/stretch