Remove the 'requirements.txt' syntax

This is needed because the syntax is only available under GPL v3.0,
which is not compatible with `bat`s license.

tests/syntax-tests/source/RequirementsTXT/requirements.txt

@@ -1,8 +0,0 @@
-#this is a sample requirements.txt file
-
-django==11.2.0
-pywheels>=12.4 #a whitespace followed by comments
-Nuitka<0.6.8.4
-wxPython>=1.0, <=2.1
-
-#this is another comment