[ruby/yarp] Fix invalid unescape sequence error for lower w

https://github.com/ruby/yarp/commit/5a2c78367a

test/yarp/fixtures/arrays.txt

@@ -78,3 +78,5 @@ foo[bar] = baz
 %w{one two three}
 
 %x{one two three}
+
+%w[\C:]

test/yarp/snapshots/arrays.txt

@@ -1,6 +1,6 @@
-ProgramNode(0...502)(
+ProgramNode(0...511)(
   [],
-  StatementsNode(0...502)(
+  StatementsNode(0...511)(
     [ArrayNode(0...4)(
        [SplatNode(1...3)(
           (1...2),
@@ -691,6 +691,11 @@ ProgramNode(0...502)(
        (488...501),
        (501...502),
        "one two three"
+     ),
+     ArrayNode(504...511)(
+       [StringNode(507...510)(nil, (507...510), nil, "\\C:")],
+       (504...507),
+       (510...511)
      )]
   )
 )

yarp/yarp.c

@@ -6477,7 +6477,14 @@ parser_lex(yp_parser_t *parser) {
                         // If we hit escapes, then we need to treat the next token
                         // literally. In this case we'll skip past the next character and
                         // find the next breakpoint.
-                        size_t difference = yp_unescape_calculate_difference(breakpoint, parser->end, YP_UNESCAPE_ALL, false, &parser->error_list);
+
+                        yp_unescape_type_t unescape_type;
+                        if (parser->lex_modes.current->as.list.interpolation) {
+                            unescape_type = YP_UNESCAPE_ALL;
+                        } else {
+                            unescape_type = YP_UNESCAPE_MINIMAL;
+                        }
+                        size_t difference = yp_unescape_calculate_difference(breakpoint, parser->end, unescape_type, false, &parser->error_list);
 
                         // If the result is an escaped newline, then we need to
                         // track that newline.