Fix python -m command error (modelcontextprotocol#387)

Co-authored-by: xzx <[email protected]>

Author: xuzexin-hz

examples/servers/simple-resource/mcp_simple_resource/__main__.py

@@ -1,5 +1,5 @@
 import sys
 
-from server import main
+from .server import main
 
 sys.exit(main())

examples/servers/simple-tool/mcp_simple_tool/__main__.py

@@ -1,5 +1,5 @@
 import sys
 
-from server import main
+from .server import main
 
 sys.exit(main())