Bump Microsoft.SourceLink.GitHub from 1.1.1 to 8.0.0 in /gremlin-dotnet #5090

Job	Run time
smoke	2m 37s
gremlin-server unified	22m 48s
mvn clean install - jdk8	13m 54s
cache gremlin-server docker image	1m 40s
gremlin-server default	24m 13s
mvn clean install - jdk11	16m 39s
gremlin-console	5m 32s
neo4j-gremlin	8m 32s
spark core (ubuntu-latest)	11m 33s
spark gryo (ubuntu-latest)	9m 35s
spark core (windows-latest)	3m 50s
spark gryo (windows-latest)	3m 47s
javascript (ubuntu-latest)	5m 39s
.NET	5m 42s
go	5m 53s
gremlin-driver	3m 47s
python	5m 54s
	2h 31m 35s

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