build: remove .txt files from .gitignore

Refs: #32670 (comment)

PR-URL: #32710
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>

.gitignore

@@ -36,7 +36,6 @@
 /*.exe
 /*.swp
 /out
-/*.txt
 
 # === Rules for artifacts of `./configure` ===
 /icu_config.gypi