Format KW macro keyword invocations onto separate lines in reserved_keywords unit test (#18)

The `KW` macro in `tests/unit/reserved_keywords.cpp` had multiple
`X(...)` invocations compressed onto one line.
This updates the definition to use one invocation per line, matching
the surrounding style.

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Nuno Lopes <nuno.lopes@tecnico.ulisboa.pt>

Author: Copilot

tests/unit/reserved_keywords.cpp

@@ -33,7 +33,14 @@
   X(final)                                                                     \
   X(gen)                                                                       \
   X(macro)                                                                     \
-  X(override) X(priv) X(unsized) X(yield) X(macro_rules) X(raw) X(safe) X(vec)
+  X(override)                                                                  \
+  X(priv)                                                                      \
+  X(unsized)                                                                   \
+  X(yield)                                                                     \
+  X(macro_rules)                                                               \
+  X(raw)                                                                       \
+  X(safe)                                                                      \
+  X(vec)
 
 // Field declaration
 #define F(n) int n;