chore: allowlist Go-standard marshal spelling in typos config (#26891)

typos-cli 1.47.x started flagging `unmarshaling` and `marshaling` as
misspellings of the British-English double-l forms.
The Go standard library uses the single-l American English spelling
throughout `encoding/json`, `encoding/xml`, etc., so these are correct
and intentional.

Adds both words to the `extend-words` allowlist so the linter accepts
the canonical Go spelling regardless of which typos version is in use.

---
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.github/workflows/typos.toml

@@ -36,6 +36,9 @@ typ = "typ"
 styl = "styl"
 edn = "edn"
 Inferrable = "Inferrable"
+# Go standard library uses American English single-l spelling throughout encoding/json etc.
+unmarshaling = "unmarshaling"
+marshaling = "marshaling"
 IIF = "IIF"
 
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