tools/github actions: set workflow names

- https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#name

.github/workflows/build.yml

@@ -1,3 +1,5 @@
+name: build
+
 on:
   push:
     branches: [ master ]

.github/workflows/daily-update-metadata.yml

@@ -1,3 +1,5 @@
+name: update metadata
+
 on:
   schedule:
     - cron: '22 22 * * *'

.github/workflows/daily-url-check.yml

@@ -1,3 +1,5 @@
+name: link checks
+
 on:
   schedule:
     - cron: '22 22 * * *'

.github/workflows/pull-request.yml

@@ -1,3 +1,5 @@
+name: pull request
+
 on:
   pull_request:
     branches: [ master ]