Update check.go

Author: CharlesCheung96

pkg/version/check.go

@@ -55,7 +55,7 @@ var (
 	defaultTiCDCVersion = semver.New("4.0.1")
 
 	// MinTiCDCVersion is the version of the minimal allowed TiCDC version.
-	MinTiCDCVersion = semver.New("7.3.0-alpha")
+	MinTiCDCVersion = semver.New("6.3.0-alpha")
 	// MaxTiCDCVersion is the version of the maximum allowed TiCDC version.
 	// for version `x.y.z`, max allowed `x+2.0.0`
 	MaxTiCDCVersion = semver.New("10.0.0-alpha")