feat: add back Python 3.7 support

We do not test the code against Python 3.7 runtime so the support might
break in the future release.

Fix #292

Author: seanwu1105

python/scripts/utils/__init__.py

@@ -5,9 +5,12 @@
 
 QT_DEPENDENCY_ARG = "vscode_extension_qt_dependency"
 
-SupportedQtDependencies = typing.Optional[
-    typing.Literal["PySide6", "PySide2", "PyQt6", "PyQt5"]
-]
+if sys.version_info < (3, 8):
+    SupportedQtDependencies = typing.Optional[str]  # pragma: no cover
+else:
+    SupportedQtDependencies = typing.Optional[
+        typing.Literal["PySide6", "PySide2", "PyQt6", "PyQt5"]
+    ]
 
 
 def is_installed(name: str) -> bool:
@@ -21,7 +24,8 @@ def parse_qt_dependency() -> SupportedQtDependencies:
         required=False,
     )
 
-    if dep := vars(parser.parse_known_args()[0])[QT_DEPENDENCY_ARG]:
+    dep = vars(parser.parse_known_args()[0])[QT_DEPENDENCY_ARG]
+    if dep is not None:
         sys.argv.remove(f"--{QT_DEPENDENCY_ARG}")
         sys.argv.remove(dep)
 

python/tests/__init__.py

@@ -1,6 +1,7 @@
 import os
 import platform
 import subprocess
+import sys
 import typing
 
 from scripts.utils import QT_DEPENDENCY_ARG, SupportedQtDependencies
@@ -11,9 +12,12 @@
 
 ASSETS_DIR = os.path.join(TESTS_DIR, "assets")
 
-SupportedScripts = typing.Literal[
-    "designer", "qml", "qmlls", "rcc", "uic", "lupdate", "linguist", "lrelease"
-]
+if sys.version_info < (3, 8):
+    SupportedScripts = str
+else:
+    SupportedScripts = typing.Literal[
+        "designer", "qml", "qmlls", "rcc", "uic", "lupdate", "linguist", "lrelease"
+    ]
 
 
 def filter_available_qt_dependencies(