Update badges

README.md

@@ -4,7 +4,7 @@ This is a meta-distribution of [RDF.rb][] including all currently available
 and usable parsing/serialization extensions, intended to make producing and
 consuming [Linked Data][] with Ruby as quick & easy as possible.
 
-[![Gem Version](https://badge.fury.io/rb/linkeddata.png)](http://badge.fury.io/rb/linkeddata)
+[![Gem Version](https://badge.fury.io/rb/linkeddata.svg)](http://badge.fury.io/rb/linkeddata)
 [![Build Status](https://github.com/ruby-rdf/linkeddata/workflows/CI/badge.svg?branch=develop)](https://github.com/ruby-rdf/linkeddata/actions?query=workflow%3ACI)
 [![Gitter chat](https://badges.gitter.im/ruby-rdf/rdf.png)](https://gitter.im/ruby-rdf/rdf)
 
@@ -159,4 +159,4 @@ see <http://unlicense.org/> or the accompanying {file:UNLICENSE} file.
 [TriX]:               http://www.w3.org/2004/03/trix/
 [Turtle]:             http://www.w3.org/TR/turtle/
 [XSD Datatypes]: http://www.w3.org/TR/2004/REC-xmlschema-2-20041028/#built-in-datatypes
-[YAML-LD]: https://json-ld.github.io/yaml-ld/spec
+[YAML-LD]: https://json-ld.github.io/yaml-ld/spec