Upgrade rust/crates/plotters-backend to 0.3.2

Test: make
Change-Id: I91a14dc3a6ebc67ea9f30f2b4f86619eae05b883
diff --git a/Cargo.toml b/Cargo.toml
index e511ae2..582dabc 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -13,7 +13,7 @@
 [package]
 edition = "2018"
 name = "plotters-backend"
-version = "0.3.0"
+version = "0.3.2"
 authors = ["Hao Hou <haohou302@gmail.com>"]
 description = "Plotters Backend API"
 homepage = "https://plotters-rs.github.io"