Moved clang-format requirement back to 3.7.

.clang-format

 BasedOnStyle: LLVM
 AlignAfterOpenBracket: true
+AlignConsecutiveAssignments: true
 IndentWidth: 4
 AlwaysBreakAfterDefinitionReturnType: None
 PenaltyReturnTypeOnItsOwnLine: 9999999

CONTRIBUTING.md

@@ -199,7 +199,7 @@ for new files, or cosmetic `tidy/*` branches, but try to stick to existing
 formatting elsewhere.
 
 Installing it is straightforward on most package managers. Nektar++ relies on
-options that are used in version 3.6 or later.
+options that are used in version 3.7 or later.
 
 There are a number of instructions on how to use `clang-format` inside a number
 of text editors on the