Update swift/third_party/resources/updating.md

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: jketema

swift/third_party/resources/updating.md

@@ -23,5 +23,5 @@ In order to perform a Swift update:
    (or whatever you have overridden). This will pull the staged archives in the repository for git LFS.
 8. Clear `_override` in [`load.bzl`](../load.bzl).
 9. Add a change note to the [library change note directory](../../ql/lib/change-notes/) that mentions that we now support the Swift version we updated to.
-10. If this not patch update, then update the [supported versions](../../../docs/codeql/reusables/supported-versions-compilers.rst) with the Swift version we updated to.
+10. If this is not a patch update, then update the [supported versions](../../../docs/codeql/reusables/supported-versions-compilers.rst) with the Swift version we updated to.
 11. Push and your PR will be ready for `main`.