PG-603: Fix/Update String::Util module in TAP test perl. (#373)

Removed use of String::Util perl module from TAP test cases, and now using
Text::Trim module instead, as that is more stable. Also removed the
Data::Str2Num perl module as it was not needed any more.

t/pgsm.pm

@@ -1,6 +1,5 @@
 package PGSM;
 
-use String::Util qw(trim);
 use File::Basename;
 use File::Compare;
 use Test::More;