replace deprecated method (#46)

diff --git a/src/main/java/org/apache/maven/plugins/shade/resource/ServicesResourceTransformer.java b/src/main/java/org/apache/maven/plugins/shade/resource/ServicesResourceTransformer.java
index 6a2bec6..929c5fa 100644
--- a/src/main/java/org/apache/maven/plugins/shade/resource/ServicesResourceTransformer.java
+++ b/src/main/java/org/apache/maven/plugins/shade/resource/ServicesResourceTransformer.java
@@ -72,7 +72,7 @@
             serviceEntries.put( resource, out );
         }
 
-        final String content = IOUtils.toString( is );
+        final String content = IOUtils.toString( is, StandardCharsets.UTF_8 );
         StringReader reader = new StringReader( content );
         BufferedReader lineReader = new BufferedReader( reader );
         String line;