clan_cli: Refactor secrets:get_public_key to use cmd.run

pkgs/clan-cli/clan_cli/secrets/sops.py

@@ -24,14 +24,13 @@ class SopsKey:
 
 def get_public_key(privkey: str) -> str:
     cmd = nix_shell(["nixpkgs#age"], ["age-keygen", "-y"])
-    try:
-        res = subprocess.run(
-            cmd, input=privkey, stdout=subprocess.PIPE, text=True, check=True
-        )
-    except subprocess.CalledProcessError as e:
-        raise ClanError(
-            "Failed to get public key for age private key. Is the key malformed?"
-        ) from e
+
+    res = run(
+        cmd,
+        input=privkey.encode("utf-8"),
+        error_msg="Failed to get public key for age private key. Is the key malformed?",
+    )
+
     return res.stdout.strip()