removing "r" in open(..., "r") is not an upgrade

[nmichlo]

While open("foo", "r") may be considered redundant, some may arguably consider it explicit instead, since It is not always immediately obvious that open("foo") defaults to read only without first consulting the python documentation.

I do, however, agree that the following is an appropriate change for pyupgrade, since the U flag is explicitly deprecated.

-open("foo", "rUb")
+open("foo", "rb")

The "r" flag on the other hand is not deprecated, rather when used it is often for readability purposes, and so removing it is a stylistic choice, not necessarily an upgrade.

[asottile]

feel free to not use the opinionated tool if you don't agree with the opinions it implements