.github: enable linter for example contracts

Signed-off-by: Anna Shaleva <shaleva.ann@nspcc.ru>

Author: AnnaShaleva

.github/workflows/tests.yml

@@ -16,6 +16,13 @@ jobs:
   lint:
     name: Lint
     uses: nspcc-dev/.github/.github/workflows/go-linter.yml@master
+
+  examples_lint:
+    name: Lint for examples
+    uses: nspcc-dev/.github/.github/workflows/go-linter.yml@master
+    with:
+      workdir: examples
+
   gomodcheck:
     name: Check internal dependencies
     runs-on: ubuntu-latest