seq: missing -f option

`seq` is missing the `-f` option:
```
       -f, --format=FORMAT
              use printf style floating-point FORMAT
```

For example,
```
$ seq -f "%.3f" 0 .1 1
0.000
0.100
0.200
0.300
0.400
0.500
0.600
0.700
0.800
0.900
1.000
```