Add oqs-arm64 runner label to actionlint config

.github/actionlint.yaml

@@ -0,0 +1,7 @@
+self-hosted-runner:
+  # Labels of self-hosted runner in array of strings.
+  labels: [oqs-arm64]
+# Configuration variables in array of strings defined in your repository or
+# organization. `null` means disabling configuration variables check.
+# Empty array means no configuration variable is allowed.
+config-variables: null