fix(ci): add actions/checkout to all 5 Upptime workflows

The Upptime action reads .upptimerc.yml from the current working
directory; without an explicit checkout step the runner starts in an
empty dir and every run fails with ENOENT. Adding actions/checkout@v4
with fetch-depth: 0 (full history required by the commit-back step)
as the first step of each workflow.

Observed on the initial-commit runs of uptime.yml + static-site.yml
which both failed with:
  ERROR [Error: ENOENT: no such file or directory, open '.upptimerc.yml']

.github/workflows/graphs.yml

@@ -12,6 +12,9 @@ jobs:
     name: Generate graphs
     runs-on: ubuntu-latest
     steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
       - uses: upptime/uptime-monitor@master
         with:
           command: "graphs"

.github/workflows/response-time.yml

@@ -13,6 +13,9 @@ jobs:
     name: Update response time graphs
     runs-on: ubuntu-latest
     steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
       - uses: upptime/uptime-monitor@master
         with:
           command: "response-time"

.github/workflows/static-site.yml

@@ -20,6 +20,9 @@ jobs:
     name: Build and deploy status site
     runs-on: ubuntu-latest
     steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
       - uses: upptime/uptime-monitor@master
         with:
           command: "site"

.github/workflows/summary.yml

@@ -12,6 +12,9 @@ jobs:
     name: Generate README + summary
     runs-on: ubuntu-latest
     steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
       - uses: upptime/uptime-monitor@master
         with:
           command: "readme"

.github/workflows/uptime.yml

@@ -20,6 +20,9 @@ jobs:
     name: Check status of endpoints
     runs-on: ubuntu-latest
     steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
       - uses: upptime/uptime-monitor@master
         with:
           command: "update"