Upgrade to dotnet 8 and bump Orleans version #1975

Job	Run time
Azure Cosmos DB provider tests	0s
Build (ubuntu-latest)	3m 45s
Azure Storage provider tests	0s
Build (windows-latest)	5m 48s
Consul provider tests (Consul)	7m 44s
AWS DynamoDB provider tests (DynamoDB)	5m 13s
MariaDB/MySQL provider tests (MySql)	4m 49s
PostgreSQL provider tests (PostgreSql)	5m 6s
Redis provider tests (Redis)	6m 53s
Microsoft SQL Server provider tests (SqlServer)	4m 35s
ZooKeeper provider tests (ZooKeeper)	4m 38s
	48m 31s

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