Upgrade rust toolchain to 1.70.0

Change-Id: I1f1b5f9a0128bfeccdf0f9fd0c1b2581612eb50b
Signed-off-by: Adam Snaider <adsnaider@gmail.com>
diff --git a/WORKSPACE b/WORKSPACE
index d2f8639..e674ad0 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -1138,8 +1138,8 @@
         "aarch64-unknown-linux-gnu",
     ],
     register_toolchain = False,
-    rustfmt_version = "1.62.0",
-    version = "1.62.0",
+    rustfmt_version = "1.70.0",
+    version = "1.70.0",
 )
 
 # Flatbuffers