Update ext/json dependency file

And update the LEGAL mentions.

LEGAL

@@ -714,10 +714,9 @@ mentioned below.
 
     {MIT License}[rdoc-ref:@MIT+License]
 
-[ext/json/vendor/ryu.h]
-  This file is adapted from the Ryu algorithm by Ulf Adams https://github.com/ulfjack/ryu.
-  It is dual-licensed under {Apache License 2.0}[rdoc-ref:@Apache+License+2.0] OR
-  {Boost Software License 1.0}[rdoc-ref:@Boost+Software+License+1.0].
+[ext/json/vendor/fast_float_parser.h]
+  This file is adapted from the Fast Float C++ library by The fast_float authors https://github.com/fastfloat/fast_float
+  It is licensed under the MIT License
 
 [ext/psych]
 [test/psych]

ext/json/parser/depend

@@ -177,6 +177,6 @@ parser.o: $(hdrdir)/ruby/subst.h
 parser.o: $(srcdir)/../fbuffer/fbuffer.h
 parser.o: $(srcdir)/../json.h
 parser.o: $(srcdir)/../simd/simd.h
-parser.o: $(srcdir)/../vendor/ryu.h
+parser.o: $(srcdir)/../vendor/fast_float_parser.h
 parser.o: parser.c
 # AUTOGENERATED DEPENDENCIES END