vs2019 preview search path added (#501)

* vs2019 preview search path added

* rust format

* rust format 2

* rust format 3

* rust format 4

* rust format 5

* rust format 6

Author: RaaliOloth8

src/windows_registry.rs

@@ -227,6 +227,11 @@ mod impl_ {
             let installation_name = instance.installation_name().ok()?;
             if installation_name.to_str()?.starts_with("VisualStudio/16.") {
                 Some(PathBuf::from(instance.installation_path().ok()?))
+            } else if installation_name
+                .to_str()?
+                .starts_with("VisualStudioPreview/16.")
+            {
+                Some(PathBuf::from(instance.installation_path().ok()?))
             } else {
                 None
             }