refactor: use explicit conversion in f-strings

gns3server/controller/topology.py

@@ -139,7 +139,7 @@ def load_topology(path):
         with open(path, encoding="utf-8") as f:
             topo = json.load(f)
     except (OSError, UnicodeDecodeError, ValueError) as e:
-        raise ControllerError(f"Could not load topology {path}: {str(e)}")
+        raise ControllerError(f"Could not load topology {path}: {e!s}")
 
     if topo.get("revision", 0) > GNS3_FILE_FORMAT_REVISION:
         raise ControllerError(
@@ -154,7 +154,7 @@ def load_topology(path):
         try:
             shutil.copy(path, path + ".backup{}".format(topo.get("revision", 0)))
         except OSError as e:
-            raise ControllerError(f"Can't write backup of the topology {path}: {str(e)}")
+            raise ControllerError(f"Can't write backup of the topology {path}: {e!s}")
         changed = True
         # update the version because we converted the topology
         topo["version"] = __version__
@@ -210,7 +210,7 @@ def load_topology(path):
             with open(path, "w+", encoding="utf-8") as f:
                 json.dump(topo, f, indent=4, sort_keys=True)
         except OSError as e:
-            raise ControllerError(f"Can't write the topology {path}: {str(e)}")
+            raise ControllerError(f"Can't write the topology {path}: {e!s}")
     return topo
 
 
@@ -326,7 +326,7 @@ def _convert_2_0_0_beta_2(topo, topo_path):
                 for path in glob.glob(os.path.join(glob.escape(dynamips_dir), "configs", f"i{dynamips_id}_*")):
                     shutil.move(path, os.path.join(node_dir, "configs", os.path.basename(path)))
             except OSError as e:
-                raise ControllerError(f"Can't convert project {topo_path}: {str(e)}")
+                raise ControllerError(f"Can't convert project {topo_path}: {e!s}")
     return topo