scan_packages: baseline sentencepiece dup2 finding after upstream reindent (#7120)

The supply-chain scan gates on non-baselined CRITICAL/HIGH findings. A newer
sentencepiece release reindented the stdout/stderr fd-redirect helper in
sentencepiece/__init__.py (the os.dup2 pair the heuristic flags as a
reverse/bind-shell pattern), moving it from L1221/L1226 to L772/L777 and
changing its leading indentation.

The baseline key is (package, package-relative file, check, evidence_hash),
where evidence_hash is over the matched code with the L<NN>: markers stripped
but the code's own indentation preserved. The reindent therefore changed the
hash (bba233.. -> 65b5a11c..), so the existing entry no longer suppressed the
finding and it resurfaced as a blocking CRITICAL in the hf-stack and studio
scan legs.

Add the new indentation variant to the allowlist. The calls are sentencepiece
redirecting stdout/stderr file descriptors to capture its C++ logs, not a
shell; no socket or networking is involved. The old L1221 entry is kept so
both versions stay covered.

scripts/scan_packages_baseline.json

@@ -634,6 +634,14 @@
       "evidence": "L1221:       os.dup2(self.ostream.fileno(), self.orig_stream_fileno) | L1226:       os.dup2(self.orig_stream_dup, self.orig_stream_fileno)",
       "evidence_hash": "bba233b67f8ea4f0723b2fecaabf56528531bccd77ace836165bf38b47246bcc"
     },
+    {
+      "package": "sentencepiece",
+      "file": "sentencepiece/__init__.py",
+      "check": "Reverse shell / bind shell pattern",
+      "severity": "CRITICAL",
+      "evidence": "L772:             os.dup2(self.ostream.fileno(), self.orig_stream_fileno) | L777:             os.dup2(self.orig_stream_dup, self.orig_stream_fileno)",
+      "evidence_hash": "65b5a11cce128fe09b3f238c01bed7c883d1740d7d46d659118f67940f6c17dc"
+    },
     {
       "package": "setuptools",
       "file": "distutils-precedence.pth",