bump up version for prerelease (#768)

conda/dgl/meta.yaml

 package:
   name: dgl{{ environ.get('DGL_PACKAGE_SUFFIX', '') }}
-  version: "0.3"
+  version: "0.4"
 
 source:
   git_rev: 0.3.x

include/dgl/runtime/c_runtime_api.h

@@ -33,7 +33,7 @@
 #endif
 
 // DGL version
-#define DGL_VERSION "0.3"
+#define DGL_VERSION "0.4"
 
 
 // DGL Runtime is DLPack compatible.

python/dgl/_ffi/libinfo.py

@@ -87,4 +87,4 @@ def find_lib_path(name=None, search_path=None, optional=False):
 # We use the version of the incoming release for code
 # that is under development.
 # The following line is set by dgl/python/update_version.py
-__version__ = "0.3"
+__version__ = "0.4"

python/update_version.py

@@ -11,7 +11,7 @@ import re
 # current version
 # We use the version of the incoming release for code
 # that is under development
-__version__ = "0.3" + os.getenv('DGL_PRERELEASE', '')
+__version__ = "0.4" + os.getenv('DGL_PRERELEASE', '')
 print(__version__)
 
 # Implementations