Fix Range#min fast path with exclusive range

mrbgems/mruby-range-ext/mrblib/range.rb

@@ -58,7 +58,6 @@ class Range
       return nil if val == last && exclude_end?
 
       min = val
-      min -= 1 if exclude_end?
       return min
     end
 

mrbgems/mruby-range-ext/test/range.rb

@@ -87,6 +87,7 @@ end
 assert('Range#min') do
   # returns the minimum value in the range when called with no arguments
   assert_equal 1, (1..10).min
+  assert_equal 1, (1...10).min
 
   # returns the minimum value in the Float range when called with no arguments
   assert_equal 303.20, (303.20..908.1111).min