QA: Apply ruff suggestions.

Author: Gadgetoid

examples/bargraph.py

@@ -1,4 +1,3 @@
-import os
 import sys
 import time
 

tests/tools.py

@@ -57,7 +57,7 @@ def __init__(self, i2c_bus):
         self.regs[0x04] = 0x02  # Control Register
 
         # Prime the Calibrated Data registers with fake data
-        self.regs[0x14:24] = [ord(c) if type(c) is str else c for c in struct.pack(
+        self.regs[0x14:24] = [ord(c) if isinstance(c, str) else c for c in struct.pack(
             '>ffffff',
             *reversed(CALIBRATED_VALUES)
         )]