tests/functional/lang: Don't use tabs for indentation

Don't ask me the fuck why, but *somehow* Nix prints error locations
differently if the input file is passed as a path vs through stdin, and
I have a hunch that this might have to do with tabs

Change-Id: I186b0edb90edd48856da3621815463e372c37512

tests/functional/lang/parse-okay-rec-set-override-warning.err.exp

@@ -1,12 +1,12 @@
 warning: __overrides attributes are deprecated and will be removed in the future. Use --extra-deprecated-features rec-set-overrides to silence this warning.
-         at «stdin»:3:16:
-              2|         # Should warn
-              3|  { a = rec {}; a.__overrides = {}; }
-               |                ^
-              4|  rec { __overrides = {}; }
+         at «stdin»:3:17:
+              2|   # Should warn
+              3|   { a = rec {}; a.__overrides = {}; }
+               |                 ^
+              4|   rec { __overrides = {}; }
 warning: __overrides attributes are deprecated and will be removed in the future. Use --extra-deprecated-features rec-set-overrides to silence this warning.
-         at «stdin»:4:8:
-              3|  { a = rec {}; a.__overrides = {}; }
-              4|    rec { __overrides = {}; }
-               |        ^
-              5|    # Should not warn: Not recursive
+         at «stdin»:4:9:
+              3|   { a = rec {}; a.__overrides = {}; }
+              4|   rec { __overrides = {}; }
+               |         ^
+              5|   # Should not warn: Not recursive

tests/functional/lang/parse-okay-rec-set-override-warning.nix

@@ -1,9 +1,9 @@
 [
-	# Should warn
-	{ a = rec {}; a.__overrides = {}; }
-	rec { __overrides = {}; }
-	# Should not warn: Not recursive
-	{ __overrides = {}; }
-	# Should not warn: Dynamic
-	rec { ${"__overrides" + ""} = {}; }
+  # Should warn
+  { a = rec {}; a.__overrides = {}; }
+  rec { __overrides = {}; }
+  # Should not warn: Not recursive
+  { __overrides = {}; }
+  # Should not warn: Dynamic
+  rec { ${"__overrides" + ""} = {}; }
 ]