ci: add electrsd, rename node to bitcoind, sort pr labels

Adds electrsd PR labelling.
Renames label node to bitcoind to match recent crate rename.
Sort PR labels in ascending alphabetical order.

Author: satsfy

.github/workflows/pr-labeler.yml

@@ -27,12 +27,13 @@ jobs:
             );
 
             const filePathsToLabels = {
-              'node/': 'C-node',
+              'bitcoind/': 'C-bitcoind',
               'client/': 'C-client',
+              'electrsd/': 'C-electrsd',
               'integration_test/': 'C-integration-test',
               'jsonrpc/': 'C-jsonrpc',
               'types/': 'C-types',
-              'verify/': 'C-verify'
+              'verify/': 'C-verify',
             };
 
             const labelsToAdd = new Set();