https://sourceforge.net/p/dblatex/patches/12/
dblatex-0.3.12-replace-imp-by-importlib.patch

https://sourceforge.net/p/dblatex/patches/13/
dblatex-0.3.12-adjust-submodule-imports.patch

Index: lib/dbtexmf/dblatex/grubber/plugins.py
--- lib/dbtexmf/dblatex/grubber/plugins.py.orig
+++ lib/dbtexmf/dblatex/grubber/plugins.py
@@ -4,7 +4,8 @@
 Mechanisms to dynamically load extra modules to help the LaTeX compilation.
 All the modules must be derived from the TexModule class.
 """
-import imp
+import importlib.machinery
+import importlib.util
 
 from os.path import *
 from dbtexmf.dblatex.grubber.msg import _, msg
@@ -108,17 +109,16 @@ class Plugins (object):
         """
         if name in self.modules:
             return 2
-        try:
-            file, path, descr = imp.find_module(name, [""])
-        except ImportError:
+        spec = importlib.machinery.PathFinder.find_spec(name, [""])
+        if not spec:
             if not self.path:
                 return 0
-            try:
-                file, path, descr = imp.find_module(name, self.path)
-            except ImportError:
-                return 0
-        module = imp.load_module(name, file, path, descr)
-        file.close()
+            spec = importlib.machinery.PathFinder.find_spec(name, self.path)
+        if not spec:
+            return 0
+        module = importlib.util.module_from_spec(spec)
+        spec.loader.exec_module(module)
+        sys.modules[name] = module
         self.modules[name] = module
         return 1
 
