The Wire library for your Uno is bundled with Arduino AVR Boards. You can verify that you have the latest version of Arduino AVR Boards by doing this:
- Tools > Board > Boards Manager
- Wait for download to finish
- Click on "Arduino AVR Boards"
- If you see an "Update" button appear then you don't have the latest version installed. If you don't see an "Update" button then you already have the latest version installed.
Note that the above instructions require you to be using a recent version of the Arduino IDE. If you are using a very old IDE version then you will not have Boards Manager. If you are using only a slightly old IDE version then you might encounter problems from updating your version of Arduino AVR Boards and if you do need to get the latest version of Arduino AVR Boards you might need to also update to the latest version of the Arduino IDE (1.8.5).