Bug when displaying `f7File()` buttons

[SCasanova]

The class .btn-file is set up as follows:

.btn-file {
    border-top-right-radius: 0 !important;
    border-bottom-right-radius: 0 !important;
}

These two lines make the left side off7File() buttons rounded and the right side straight.

Tried to fix and PR, but I was unable to find the class on quick glance.