update README.md for v8.4.0 (#204)

Signed-off-by: kpenfound <kyle@dagger.io>

Author: kpenfound

README.md

@@ -6,7 +6,7 @@
 
 ```yaml
 - name: Hello
-  uses: dagger/dagger-for-github@v8.3.0
+  uses: dagger/dagger-for-github@v8.4.0
   with:
     check: "**"
     version: "latest"  # semver vX.Y.Z
@@ -18,7 +18,7 @@ Note: As a convenience for `dagger check` you can use the [dagger/checks](https:
 
 ```yaml
 - name: Hello
-  uses: dagger/dagger-for-github@v8.3.0
+  uses: dagger/dagger-for-github@v8.4.0
   with:
     module: github.com/shykes/daggerverse/hello
     call: hello --greeting Hola --name Jeremy
@@ -30,7 +30,7 @@ Note: As a convenience for `dagger check` you can use the [dagger/checks](https:
 
 ```yaml
 - name: Hello
-  uses: dagger/dagger-for-github@v8.3.0
+  uses: dagger/dagger-for-github@v8.4.0
   with:
     shell: container | from alpine | with-exec echo,"hello, world!" | stdout
     cloud-token: ${{ secrets.DAGGER_CLOUD_TOKEN }}
@@ -40,7 +40,7 @@ Note: As a convenience for `dagger check` you can use the [dagger/checks](https:
 
 ```yaml
 - name: Integration Test
-  uses: dagger/dagger-for-github@v8.3.0
+  uses: dagger/dagger-for-github@v8.4.0
   with:
     workdir: db-service
     verb: run