Bug 1799489 - Exclude S/MIME test data-gen scripts from shellcheck. r=dandarnell

Can revisit later, in the meantime these scripts are not critical build scripts
or anything.

Differential Revision: https://phabricator.services.mozilla.com/D162106

--HG--
extra : moz-landing-system : lando

tools/lint/shellcheck.yml

@@ -3,7 +3,9 @@ shellcheck:
     description: Shell script linter
     include:
         - comm/
-    exclude: []
+    exclude:
+        - comm/mailnews/test/data/smime/generate.sh
+        - comm/mailnews/test/data/smime/local-gen.sh
     # 1090: https://github.com/koalaman/shellcheck/wiki/SC1090
     # 'Can't follow a non-constant source'
     extensions: ['sh']