Update metadata to reflect addition of support for UNO R4 boards

[per1234]

The architectures field of the library.properties metadata file specifies a list of architectures supported by the library.

Previously, the renesas_uno architecture was not included in this list, even though that architecture is supported by the library (622ac13). This resulted in several undesirable outcomes when compiling the library for boards of that architecture:

• Display of a misleading warning when compiling the library:

  WARNING: library TimerOne claims to run on avr architecture(s) and may be incompatible with your current board which runs on renesas_uno architecture(s).
  

• Library discovery phase of the sketch build system giving higher priority to other installed libraries matching an #include directive intended to target this library.
• Library's examples placed under the Arduino IDE 1.x File > Examples > INCOMPATIBLE menu.

These problems are resolved by adding the missing architectures to the architectures field.

When installed via Boards manager, the "Arduino R4 UNO Boards" platform has the architecture renesas_uno. This platform is part of the arduino/ArduinoCore-renesas repository, which provides support for other boards based on Renesas microcontrollers in addition to the UNO R4 family. When the platform is installed manually for development or beta testing, the renesas_uno architecture is not appropriate and so the convention is to instead use the general renesas architecture for manual installations of the platform. For this reason, the renesas architecture was also added to the field in order to support the use of the library with manually installed copies of the platform in addition to Boards Manager installations.

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Originally reported at https://forum.arduino.cc/t/timer-interrupt-uno-r4-minima/1146816/9