Fix spdx license key error

Signed-off-by: Ayan Sinha Mahapatra <[email protected]>

Author: AyanSinhaMahapatra

src/licensedcode/data/licenses/pnmstitch.LICENSE

@@ -6,8 +6,6 @@ category: Permissive
 owner: pnmstitch Project
 notes: This is the same as bsd-dpt.RULE with ` Mark Salyzyn` added.
 spdx_license_key: pnmstitch
-other_spdx_license_keys:
-    - pnmstitc
 other_urls:
     - https://sourceforge.net/p/netpbm/code/HEAD/tree/super_stable/editor/pnmstitch.c#l2
 ---