doc: fix typo in maintaining-dependencies.md

PR-URL: https://github.com/nodejs/node/pull/45428
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

doc/contributing/maintaining-dependencies.md

@@ -67,7 +67,7 @@ shared library is available can added by:
   If there are additional libraries that are required it is
   possible to list more than one with the `pkgname` option.
 * in `node.gypi` guard the build for the dependency
-  with `node_shared_depname` so that is is only built if
+  with `node_shared_depname` so that it is only built if
   the dependency is being bundled into Node.js itself. For example:
 
 ```text