seq: padding of `-w` is incorrect if scientific notation uses `E` instead of `e`

I noticed that when using `-w`/`--equal-width`, the output is correct with `e` but not with `E`:

```
$ cargo run -q seq -w 0e15 1
0000000000000000
0000000000000001
$ cargo run -q seq -w 0E15 1
0000000000000000
0001
$ seq -w 0e15 1
0000000000000000
0000000000000001
$ seq -w 0E15 1
0000000000000000
0000000000000001
```