Model updates: eCLM with new snow thermal conductivity options; ParFlow with more CUDA13 fixes (#124)

* Updated eCLM to beta-0.6
* Updated ParFlow to v3.15.0

Author: kvrigor

.gitmodules

@@ -4,8 +4,8 @@
 	branch = icon-2024.07-public_coup-oas
 [submodule "models/parflow"]
 	path = models/parflow
-	url = https://github.com/HPSCTerrSys/parflow.git
-	branch = fixes-cuda13-oasis3
+	url = https://github.com/parflow/parflow.git
+	branch = v3.15.0
 [submodule "models/parflow_pdaf"]
 	path = models/parflow_pdaf
 	url = https://github.com/HPSCTerrSys/parflow
@@ -17,7 +17,7 @@
 [submodule "models/eCLM"]
 	path = models/eCLM
 	url = https://github.com/HPSCTerrSys/eCLM.git
-	branch = beta-0.5
+	branch = beta-0.6
 [submodule "models/oasis3-mct"]
         path = models/oasis3-mct
         url = https://icg4geo.icg.kfa-juelich.de/ExternalReposPublic/oasis3-mct