tests: Trim .nim files trailing whitespace

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

tests/overload/toverwr.nim

@@ -1,13 +1,13 @@
-discard """
-  file: "toverwr.nim"
-  output: "hello"
-"""
-# Test the overloading resolution in connection with a qualifier
-
-proc write(t: TFile, s: string) =
-  discard # a nop
-
-system.write(stdout, "hello")
-#OUT hello
-
-
+discard """
+  file: "toverwr.nim"
+  output: "hello"
+"""
+# Test the overloading resolution in connection with a qualifier
+
+proc write(t: TFile, s: string) =
+  discard # a nop
+
+system.write(stdout, "hello")
+#OUT hello
+
+