Remove 'the' as suggested by Quentin

chapters/interface.tex

@@ -537,7 +537,7 @@ \section{Function-Compatibility or Function-Subtyping for Functions}\label{funct
   constraining interface of the function being redeclared.
 \end{itemize}
 
-Note that variability of function calls cannot be determined using the just the interface of a function, as the variabilities of default argument expressions are not expressed by the interface.
+Note that variability of function calls cannot be determined using just the interface of a function, as the variabilities of default argument expressions are not expressed by the interface.
 Hence a function redeclaration being function-compatible does not ensure that function calls will fulfill variability requirements, and tools must therefore check variability requirements separately.
 
 \begin{nonnormative}