src/codal_app: Update codal-microbit-v2 to v0.2.25.

Main changes are:
- bug fixes for UART/Serial buffers and race conditions
- enable errata for I2C and improve I2C at high speed
- use floats to compute mixer sampling rate for better accuracy

Signed-off-by: Damien George <damien@micropython.org>

Author: dpgeorge

src/codal_app/codal.json

@@ -2,7 +2,7 @@
     "target": {
         "name": "codal-microbit-v2",
         "url": "https://github.com/lancaster-university/codal-microbit-v2",
-        "branch": "v0.2.24",
+        "branch": "v0.2.25",
         "type": "git",
         "test_ignore": true
     } ,