Use importlib.metadata instead of pkg_resources for version queries.

pkg_resources is a legacy setuptools API. importlib.metadata (stdlib since
Python 3.8) is the correct replacement and requires no extra runtime dependency.

--- a/nvr/nvr.py
+++ b/nvr/nvr.py
@@ -360,10 +360,10 @@


 def print_versions():
-    import pkg_resources
-    print('nvr ' + pkg_resources.require("neovim-remote")[0].version)
-    print('pynvim ' + pkg_resources.require('pynvim')[0].version)
-    print('psutil ' + pkg_resources.require('psutil')[0].version)
+    from importlib.metadata import version
+    print('nvr ' + version("neovim-remote"))
+    print('pynvim ' + version('pynvim'))
+    print('psutil ' + version('psutil'))
     print('Python ' + sys.version.split('\n')[0])