BAD SIGNATURE when installing on Alpine Linux

Hello,

recently our Docker builds started to fail when trying to install APM agent from the APK package. The reason they fail is:

```ERROR: apm-agent-php-1.13.0: BAD signature```

This is the case with Alpine 3.17, Alpine 3.18 and Alpine 3.19 and with APM agent versions 1.12 and 1.13.

You can reproduce this by trying to build this Dockerfile:
```
FROM docker.io/alpine:3.19 as base

RUN apk update && apk upgrade
RUN apk add ca-certificates wget && wget -q https://github.com/elastic/apm-agent-php/releases/download/v1.13.0/apm-agent-php_1.13.0_x86_64.apk
RUN apk add --allow-untrusted apm-agent-php_1.13.0_x86_64.apk
```

Thanks for checking this out !