v8.0 module release (#22975)

https://mattermost.atlassian.net/browse/MM-52079

```release-note
We upgrade the module version to 8.0. The new module path is github.com/mattermost-server/server/v8.
```


Co-authored-by: Doug Lauder <wiggin77@warpmail.net>

server/platform/shared/driver/conn.go

@@ -7,7 +7,7 @@ import (
 	"context"
 	"database/sql/driver"
 
-	"github.com/mattermost/mattermost-server/v6/plugin"
+	"github.com/mattermost/mattermost-server/server/v8/plugin"
 )
 
 // Conn is a DB driver conn implementation

server/platform/shared/driver/driver.go

@@ -12,7 +12,7 @@ import (
 	"context"
 	"database/sql/driver"
 
-	"github.com/mattermost/mattermost-server/v6/plugin"
+	"github.com/mattermost/mattermost-server/server/v8/plugin"
 )
 
 var (

server/platform/shared/driver/objects.go

@@ -7,7 +7,7 @@ import (
 	"context"
 	"database/sql/driver"
 
-	"github.com/mattermost/mattermost-server/v6/plugin"
+	"github.com/mattermost/mattermost-server/server/v8/plugin"
 )
 
 type wrapperTx struct {