bump viridis version (#557)

* bump viridis version which bumps viridisLite version to avoid namespace export issue

* news item

Author: schloerke

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: leaflet
 Type: Package
 Title: Create Interactive Web Maps with the JavaScript 'Leaflet' Library
-Version: 2.0.1
+Version: 2.0.1.9000
 Authors@R: c(
       person("Joe", "Cheng", email = "[email protected]", role = c("aut", "cre")),
       person("Bhaskar", "Karambelkar", role = c("aut")),
@@ -50,7 +50,7 @@ Imports:
     scales (>= 0.2.5),
     sp,
     stats,
-    viridis
+    viridis (>= 0.5.1)
 Suggests:
     knitr,
     maps,

NEWS

@@ -1,3 +1,9 @@
+leaflet 2.0.1.9000
+--------------------------------------------------------------------------------
+
+BUG FIXES and IMPROVEMENTS
+* Require viridis >= 0.5.1 to avoid namespace issues with viridisLite (#557)
+
 leaflet 2.0.1
 --------------------------------------------------------------------------------