MNT: Update version detection

Try to avoid pulling in setuptools_scm for better import time by
directly checking for a pip file that indicates whether the install is
editable and only using the git-based version in that case; otherwise,
depend on the distribution metadata.

src/metpy/_version.py

@@ -8,16 +8,29 @@ def get_version():
     """Get MetPy's version.
 
     Either get it from package metadata, or get it using version control information if
-    a development install.
+    an editable installation.
     """
+    from importlib.metadata import distribution, PackageNotFoundError
+
     try:
-        from setuptools_scm import get_version
-        return get_version(root='../..', relative_to=__file__,
-                           version_scheme='post-release')
-    except (ImportError, LookupError):
-        from importlib.metadata import PackageNotFoundError, version
-
-        try:
-            return version(__package__)
-        except PackageNotFoundError:
-            return 'Unknown'
+        dist = distribution(__package__)
+
+        # First see if we can find this file from pip to check for an editable install
+        if direct := dist.read_text('direct_url.json'):
+            import json
+
+            # Parse file and look for editable key
+            info = json.loads(direct)
+            if info.get('dir_info', {}).get('editable'):
+                import contextlib
+
+                # If editable try to get version using setuptools_scm
+                with contextlib.suppress(ImportError, LookupError):
+                    from setuptools_scm import get_version
+                    return get_version(root='../..', relative_to=__file__,
+                                       version_scheme='post-release')
+
+        # With any error or not an editable install, we use the version from the metadata
+        return dist.version
+    except PackageNotFoundError:
+        return 'Unknown'