Update sl container for sl7 to current (build-date=20210504)
@@ -7,4 +7,4 @@ Tags: 7, latest
Architectures: amd64
GitFetch: refs/heads/7
Directory: sl7
-GitCommit: 8958d164f9b5f50ab9790394a30cd9e449627bf9
+GitCommit: 979e472bf649dd7641a50a617d9f57be8324a6df
yosifkit