re2: pattern trimming causes issues with trailing characters

[nvpivot]

We ran into an issue when using pattern recognition on a value that had the last character of the number 2.

Example:
re2: ^myregex2
Will result in ^myregex without the "2"

The strings.Trim(mystring, 123g) will strip the characters 1,2,3, and g from 'mystring'. So presumably, folks would hit an issue if 'r,e,2, or :' are the last character of the regex pattern.

Suggest changing this line in (https://github.com/alexei-led/pumba/blob/master/pkg/chaos/command.go)
pattern = strings.Trim(first, Re2Prefix)
TO
pattern = strings.TrimSpace(strings.TrimPrefix(first, Re2Prefix))

[alexei-led]

@nvpivot Thank you for issue report. Definitely a bug.