Upgrade rust version for RTD

Author: saulshanabrook

.readthedocs.yaml

@@ -12,7 +12,7 @@ build:
     python: "3.10"
     # You can also specify other tool versions:
     # nodejs: "16"
-    rust: "1.61"
+    rust: "1.64"
     # golang: "1.17"
 
 # Build documentation in the docs/ directory with Sphinx