[Chore] Replace all base64 usages with faster pybase64 package (#37290)

Signed-off-by: Isotr0py <mozf@mail2.sysu.edu.cn>

tools/pre_commit/check_forbidden_imports.py

@@ -59,6 +59,14 @@ CHECK_IMPORTS = {
             "vllm/v1/serial_utils.py",
         },
     ),
+    "base64": ForbiddenImport(
+        pattern=r"^\s*(?:import\s+base64(?:$|\s|,)|from\s+base64\s+import)",
+        tip=(
+            "Replace 'import base64' with 'import pybase64' "
+            "or 'import pybase64 as base64'."
+        ),
+        allowed_pattern=re.compile(r"^\s*import\s+pybase64(\s*|\s+as\s+base64\s*)$"),
+    ),
     "re": ForbiddenImport(
         pattern=r"^\s*(?:import\s+re(?:$|\s|,)|from\s+re\s+import)",
         tip="Replace 'import re' with 'import regex as re' or 'import regex'.",