[NUCLEO_F207ZG] Add MBED5 capability

Author: jeromecoutant

hal/targets.json

@@ -703,7 +703,7 @@
         "detect_code": ["0835"],
         "device_has": ["ANALOGIN", "ANALOGOUT", "CAN", "I2C", "I2CSLAVE", "INTERRUPTIN", "PORTIN", "PORTINOUT", "PORTOUT", "PWMOUT", "RTC", "SERIAL", "SLEEP", "SPI", "SPISLAVE", "STDIO_MESSAGES"],
         "features": ["IPV4"],
-        "release_versions": ["2"]
+        "release_versions": ["2", "5"]
     },
     "NUCLEO_F302R8": {
         "supported_form_factors": ["ARDUINO", "MORPHO"],