style: fix F841 local variable is assigned to but never used

src/trezor/loop.py

@@ -97,7 +97,7 @@ def _step(task, value):
             result = task.throw(value)
         else:
             result = task.send(value)
-    except StopIteration as e:
+    except StopIteration:  # as e:
         if __debug__:
             log.debug(__name__, "finish: %s", task)
     except Exception as e:

src/trezor/wire/__init__.py

@@ -154,7 +154,7 @@ async def protobuf_workflow(ctx, reader, handler, *args):
         # respond with specific code and message
         await ctx.write(Failure(code=exc.code, message=exc.message))
         raise
-    except Exception as exc:
+    except Exception:  # as exc:
         # respond with a generic code and message
         await ctx.write(
             Failure(code=FailureType.FirmwareError, message="Firmware error")