gptel-gemini: Fix Temperature parameter mapping

* gptel-gemini.el (gptel--request-data): Ensure the Gemini backend
respects temperature settings below 1.0.  Previously, the code
used (max gptel-temperature 1.0), which effectively ignored any
user setting in the 0.0-0.9 range.  Fixes #1312.

Author: Jeremias-A-Queiroz

gptel-gemini.el

@@ -152,7 +152,7 @@ list."
     (when gptel-temperature
       (setq params
             (plist-put params
-                       :temperature (max gptel-temperature 1.0))))
+                       :temperature (max 0.0 gptel-temperature))))
     (when gptel-max-tokens
       (setq params
             (plist-put params