installation guide: fix url of env_climada.yml file

(cherry picked from commit 7376986)

Author: emanuel-schmid

doc/guide/Guide_Installation.ipynb

@@ -73,7 +73,7 @@
     "Download the environment specification file from the git repository and save it locally, then create the conda environment:\n",
     "\n",
     "```bash\n",
-    "wget https://github.com/CLIMADA-project/climada_python/blob/main/requirements/env_climada.yml\n",
+    "wget https://github.com/CLIMADA-project/climada_python/raw/main/requirements/env_climada.yml\n",
     "conda env create -n climada_env -f env_climada.yml\n",
     "conda activate climada_env\n",
     "```\n",