tests: Trim .nim files trailing whitespace

via OSX: find . -name '*.nim' -exec sed -i '' -E 's/[[:space:]]+$//' {} +

tests/ambsym/mambsym1.nim

@@ -1,10 +1,10 @@
-import mambsym2 # import TExport
-
-type
-  TExport* = enum x, y, z
-  TOtherEnum* = enum mDec, mInc, mAssign
-
-proc ha() =
-  var
-    x: TExport # no error
-  discard
+import mambsym2 # import TExport
+
+type
+  TExport* = enum x, y, z
+  TOtherEnum* = enum mDec, mInc, mAssign
+
+proc ha() =
+  var
+    x: TExport # no error
+  discard