add triplets for r versions 4.3, 4.4

otherwise r-4.3 won't work

repo2docker/buildpacks/r.py

@@ -69,6 +69,8 @@ class RBuildPack(PythonBuildPack):
         """
         # Available versions at https://cran.r-project.org/src/base/
         version_map = {
+            "4.4": "4.4.1",
+            "4.3": "4.3.3",
             "4.2": "4.2.1",
             "4.1": "4.1.3",
             "4.0": "4.0.5",