Update for I2C BusDevice read/write rename.

Author: tannewt

adafruit_ds1307.py

@@ -74,8 +74,8 @@ def __init__(self, i2c):
         buf = bytearray(2)
         buf[0] = 0x07
         with self.i2c_device as i2c:
-            i2c.writeto(buf, end=1, stop=False)
-            i2c.readfrom_into(buf, start=1)
+            i2c.write(buf, end=1, stop=False)
+            i2c.read_into(buf, start=1)
 
         if (buf[1] & 0b00000011) != 0b00000011:
             raise ValueError("Unable to find DS1307 at i2c address 0x68.")