Fix linting and type errors for CI

- Use X | None syntax instead of Optional[X] (UP045)
- Sort imports in dashboard app (I001)
- Remove unnecessary UTF-8 encoding argument (UP012)
- Add 'from err' to exception re-raises (B904)
- Remove unused imports in integration tests (F401)
- Fix useless expression in test (B018)
- Cast **1.5 result to float in LDO model (mypy no-any-return)
- Use functools.partial instead of lambda in server (mypy misc)

src/py_dvt_ate/simulation/virtual/power_supply.py

@@ -94,8 +94,8 @@ class PowerSupplySim(BaseInstrument):
 
         try:
             voltage = float(command.arguments[0])
-        except ValueError:
-            raise ValueError(f"Invalid voltage value: {command.arguments[0]}")
+        except ValueError as err:
+            raise ValueError(f"Invalid voltage value: {command.arguments[0]}") from err
 
         if voltage < 0:
             raise ValueError("Voltage cannot be negative")
@@ -127,8 +127,8 @@ class PowerSupplySim(BaseInstrument):
 
         try:
             current = float(command.arguments[0])
-        except ValueError:
-            raise ValueError(f"Invalid current value: {command.arguments[0]}")
+        except ValueError as err:
+            raise ValueError(f"Invalid current value: {command.arguments[0]}") from err
 
         if current < 0:
             raise ValueError("Current limit cannot be negative")