core/deps: Add ExtProxy dep (socks proxy support)

sockshandler.py from PySocks is not maintained anymore:
  Anorov/PySocks#134

phpsploit is now using Extproxy to supports socks proxy,
as kindly advised by @SeaHOH

phpsploit

@@ -28,16 +28,17 @@ if ver[0] < 3 or (ver[0] == 3 and ver[1] < 5):
 
 # check dependencies
 from importlib.util import find_spec
-missing_deps = []
+missing_deps = set()
 deps_list = {
         "phpserialize": ("phpserialize",),
         "pyparsing":    ("pyparsing",),
-        "PySocks":      ("socks", "sockshandler"),
+        "PySocks":      ("socks", "sockshandler",),
+        "ExtProxy":     ("extproxy",),
         }
 for name, deps in deps_list.items():
     for dep in deps:
         if find_spec(dep) is None:
-            missing_deps.append(name)
+            missing_deps.add(name)
             break
 if missing_deps:
     for name in missing_deps:

requirements.txt

@@ -10,7 +10,9 @@ pyparsing==3.0.9
 
 # Needed by the PROXY setting to support socks4/5 proxy types
 PySocks==1.7.1
-
+# Needed since sockshandler.py (from Pysocks) maintenance has been stopped:
+#  https://github.com/Anorov/PySocks/issues/134#issuecomment-1310323763
+ExtProxy==1.0.1
 
 ### optional dependencies
 ##########################