Demo only supports ARM hosts

When I try to this demo on x86-64 machine, it causes following error in fluent-bit container:
```
$ docker compose up --build
WARN[0000] /home/watson/src/fluent-bit-observability-demo/docker-compose.yml: the attribute `version` is obsolete, it will be ignored, please remove it to avoid potential confusion
[+] Building 3.2s (20/20) FINISHED docker:default
=> [fluentbit internal] load build definition from Dockerfile 0.0s
=> => transferring dockerfile: 245B 0.0s
=> [fluentbit internal] load metadata for docker.io/pwhelan/fluent-bit:2.0.0-a9c7aef87 1.6s
=> [fluentbit internal] load .dockerignore 0.0s
=> => transferring context: 2B 0.0s
=> [fluentbit 1/3] FROM docker.io/pwhelan/fluent-bit:2.0.0-a9c7aef87@sha256:47ee4531eb56c239b3b61bd4ef88941a4464e66ccccef725e4bdeac67a433ff7 0.0s
=> [fluentbit internal] load build context 0.0s
=> => transferring context: 33B 0.0s
=> CACHED [fluentbit 2/3] WORKDIR /fb 0.0s
=> CACHED [fluentbit 3/3] COPY ./fluent.conf . 0.0s
=> [fluentbit] exporting to image 0.0s
=> => exporting layers 0.0s
=> => writing image sha256:f6e8dc0d7bb900d118a2b05c5690bb48c393d393d0ae4a038b5439cb12bc7b07 0.0s
=> => naming to docker.io/library/fluent-bit-observability-demo-fluentbit 0.0s
=> [fluentbit] resolving provenance for metadata file 0.0s
=> [demo_app internal] load build definition from Dockerfile 0.0s
=> => transferring dockerfile: 180B 0.0s
=> [demo_app internal] load metadata for docker.io/library/node:16 1.1s
=> [demo_app internal] load .dockerignore 0.0s
=> => transferring context: 2B 0.0s
=> [demo_app 1/5] FROM docker.io/library/node:16@sha256:f77a1aef2da8d83e45ec990f45df50f1a286c5fe8bbfb8c6e4246c6389705c0b 0.0s
=> [demo_app internal] load build context 0.0s
=> => transferring context: 162B 0.0s
=> CACHED [demo_app 2/5] WORKDIR /usr/src/app 0.0s
=> CACHED [demo_app 3/5] COPY package*.json ./ 0.0s
=> CACHED [demo_app 4/5] RUN npm install 0.0s
=> CACHED [demo_app 5/5] COPY . . 0.0s
=> [demo_app] exporting to image 0.0s
=> => exporting layers 0.0s
=> => writing image sha256:ba212fb834241562a9792be52094ff36498dfd73d37449f0f166a5036d42744d 0.0s
=> => naming to docker.io/library/fluent-bit-observability-demo-demo_app 0.0s
=> [demo_app] resolving provenance for metadata file 0.0s
[+] Running 10/10
✔ demo_app Built 0.0s
! fluentbit The requested image's platform (linux/arm64/v8) does not match the detected host platform (linux/amd64/v4) and no specific platform was requested 0.6s
✔ Network fluent-bit-observability-demo_default Created 0.2s
✔ Container grafana Created 0.3s
✔ Container fluent-bit-observability-demo-jaeger-1 Created 0.3s
✔ Container fluent-bit-observability-demo-vivo-1 Created 0.3s
✔ Container fluent-bit-observability-demo-prometheus-1 Created 0.3s
✔ Container fluent-bit-observability-demo-collector-1 Created 0.2s
✔ Container fluent-bit-observability-demo-fluentbit-1 Created 0.1s
✔ Container fluent-bit-observability-demo-demo_app-1 Created 0.1s
Attaching to collector-1, demo_app-1, fluentbit-1, jaeger-1, prometheus-1, vivo-1, grafana
collector-1 | Error: failed to get config: cannot unmarshal the configuration: decoding failed due to the following error(s):
collector-1 |
collector-1 | error decoding 'exporters': the logging exporter has been deprecated, use the debug exporter instead
collector-1 | 2025/02/19 07:19:43 collector server run finished with error: failed to get config: cannot unmarshal the configuration: decoding failed due to the following error(s):
collector-1 |
collector-1 | error decoding 'exporters': the logging exporter has been deprecated, use the debug exporter instead

... (snip) ...

fluentbit-1 | exec /fluent-bit/bin/fluent-bit: exec format error
fluentbit-1 | exec /fluent-bit/bin/fluent-bit: exec format error
fluentbit-1 exited with code 255
```

https://github.com/fluent/fluent-bit-observability-demo/blob/c6a2534ae64efe28d038c134f462d3ed81b64fd3/fluentbit/Dockerfile#L1

Seems that `pwhelan/fluent-bit:2.0.0-a9c7aef87` only provides ARM image, it can't run on x86-64 machine.
https://hub.docker.com/r/pwhelan/fluent-bit/tags?name=2.0.0-a9c7aef87

I'd like to run demo on my machine.

Thanks.