Update pyproject.toml

pyproject.toml

@@ -35,16 +35,15 @@ dependencies = [
     "pandas>=1.0.5",
     "ruamel.yaml>=0.16",
     "scipy>=1.4",
-    "importlib-resources; python_version < '3.9'",  # TODO: remove when minimum python version is 3.9
 ]
 dynamic = ["version"]
 
 [project.optional-dependencies]
 tqdm = ["tqdm>=4.41.0"]
-termset = ["linkml-runtime>=1.5.5; python_version >= '3.9'",
-           "schemasheets>=0.1.23; python_version >= '3.9'",
-           "oaklib>=0.5.12; python_version >= '3.9'",
-           "pyyaml>=6.0.1; python_version >= '3.9'"]
+termset = ["linkml-runtime>=1.5.5",
+           "schemasheets>=0.1.23",
+           "oaklib>=0.5.12",
+           "pyyaml>=6.0.1"]
 
 [project.urls]
 "Homepage" = "https://github.com/hdmf-dev/hdmf"