Remove replace directives and use own fork to make go get work again (#1028)

See https://github.com/golang/go/issues/30354
go get doesn't honor the go.mod replace options.

vendor/github.com/matterbridge/msgraph.go/beta/ShipmentMethodModel.go

@@ -0,0 +1,17 @@
+// Code generated by msgraph-generate.go DO NOT EDIT.
+
+package msgraph
+
+import "time"
+
+// ShipmentMethod undocumented
+type ShipmentMethod struct {
+	// Entity is the base model of ShipmentMethod
+	Entity
+	// Code undocumented
+	Code *string `json:"code,omitempty"`
+	// DisplayName undocumented
+	DisplayName *string `json:"displayName,omitempty"`
+	// LastModifiedDateTime undocumented
+	LastModifiedDateTime *time.Time `json:"lastModifiedDateTime,omitempty"`
+}