fix(oonimkall): export CheckInConfig.RunType (#752)

This commit cherry-picks e3e3b61 from release/3.15.

See https://github.com/ooni/probe/issues/2110 for context.

pkg/oonimkall/session.go

@@ -366,7 +366,7 @@ type CheckInConfig struct {
 
 	// RunType indicates whether this is an automated (model.RunTypeTimed) run
 	// or otherwise a manual run initiated by the user.
-	RunType model.RunType
+	RunType string
 
 	// SoftwareName is the name of the application.
 	SoftwareName string
@@ -472,7 +472,7 @@ func (sess *Session) CheckIn(ctx *Context, config *CheckInConfig) (*CheckInInfo,
 		Platform:        config.Platform,
 		ProbeASN:        info.ASNString(),
 		ProbeCC:         info.CountryCode,
-		RunType:         config.RunType,
+		RunType:         model.RunType(config.RunType),
 		SoftwareVersion: config.SoftwareVersion,
 		WebConnectivity: config.WebConnectivity.toModel(),
 	}