Bump docker/login-action from 3 to 4

Bumps [docker/login-action](https://github.com/docker/login-action) from 3 to 4.
- [Release notes](https://github.com/docker/login-action/releases)
- [Commits](docker/login-action@v3...v4)

---
updated-dependencies:
- dependency-name: docker/login-action
  dependency-version: '4'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -63,7 +63,7 @@ jobs:
 
     # GITHUB_TOKEN is unreliable¹ so use a token from nextstrain-bot.
     # ¹ https://github.com/docker/build-push-action/issues/463#issuecomment-939394233
-    - uses: docker/login-action@v3
+    - uses: docker/login-action@v4
       with:
         registry: ghcr.io
         username: nextstrain-bot
@@ -107,7 +107,7 @@ jobs:
     env:
       TAG: ${{ needs.vars.outputs.tag }}
     steps:
-    - uses: docker/login-action@v3
+    - uses: docker/login-action@v4
       with:
         registry: ghcr.io
         username: nextstrain-bot
@@ -150,7 +150,7 @@ jobs:
       contents: read
       id-token: write
     steps:
-    - uses: docker/login-action@v3
+    - uses: docker/login-action@v4
       with:
         registry: ghcr.io
         username: nextstrain-bot
@@ -196,7 +196,7 @@ jobs:
 
     - uses: docker/setup-qemu-action@v3
 
-    - uses: docker/login-action@v3
+    - uses: docker/login-action@v4
       with:
         registry: ghcr.io
         username: nextstrain-bot
@@ -214,13 +214,13 @@ jobs:
     steps:
     - uses: actions/checkout@v6
 
-    - uses: docker/login-action@v3
+    - uses: docker/login-action@v4
       with:
         registry: ghcr.io
         username: nextstrain-bot
         password: ${{ secrets.GH_TOKEN_NEXTSTRAIN_BOT_MANAGE_PACKAGES }}
 
-    - uses: docker/login-action@v3
+    - uses: docker/login-action@v4
       with:
         registry: docker.io
         username: nextstrainbot
@@ -238,13 +238,13 @@ jobs:
     steps:
     - uses: actions/checkout@v6
 
-    - uses: docker/login-action@v3
+    - uses: docker/login-action@v4
       with:
         registry: ghcr.io
         username: nextstrain-bot
         password: ${{ secrets.GH_TOKEN_NEXTSTRAIN_BOT_MANAGE_PACKAGES }}
 
-    - uses: docker/login-action@v3
+    - uses: docker/login-action@v4
       with:
         registry: docker.io
         username: nextstrainbot