Update release workflow package upload

[dhurley]

Proposed changes

Created a new directory to store the packages that need to be uploaded to a github release.
The reason being is that some packages need to be renamed to avoid conflicts during the upload.

Example of github packages to be uploaded:

./build/github/packages/nginx-agent-2.21.0.el8.ngx.x86_64.rpm
./build/github/packages/nginx-agent-2.21.0-v3.13-aarch64.apk
./build/github/packages/nginx-agent-2.21.0.sles15.ngx.x86_64.rpm
./build/github/packages/nginx-agent-2.21.0.sles12.ngx.x86_64.rpm
./build/github/packages/nginx-agent-2.21.0-v3.15-aarch64.apk
./build/github/packages/nginx-agent-2.21.0~bionic_amd64.deb
./build/github/packages/nginx-agent-2.21.0~buster_arm64.deb
./build/github/packages/nginx-agent-2.21.0~bullseye_arm64.deb
./build/github/packages/nginx-agent-2.21.0-v3.15-x86_64.apk
./build/github/packages/nginx-agent-2.21.0~focal_amd64.deb
./build/github/packages/nginx-agent-2.21.0~bionic_arm64.deb
./build/github/packages/nginx-agent-2.21.0~focal_arm64.deb
./build/github/packages/nginx-agent-2.21.0-v3.14-x86_64.apk
./build/github/packages/nginx-agent-2.21.0-v3.16-aarch64.apk
./build/github/packages/nginx-agent-2.21.0~bullseye_amd64.deb
./build/github/packages/nginx-agent-2.21.0-FreeBSD:13:amd64.pkg
./build/github/packages/nginx-agent-2.21.0.el7.ngx.x86_64.rpm
./build/github/packages/nginx-agent-2.21.0.el9.ngx.x86_64.rpm
./build/github/packages/nginx-agent-2.21.0-v3.14-aarch64.apk
./build/github/packages/nginx-agent-2.21.0~buster_amd64.deb
./build/github/packages/nginx-agent-2.21.0-v3.13-x86_64.apk
./build/github/packages/nginx-agent-2.21.0~jammy_arm64.deb
./build/github/packages/nginx-agent-2.21.0-FreeBSD:12:amd64.pkg
./build/github/packages/nginx-agent-2.21.0.amzn2.ngx.x86_64.rpm
./build/github/packages/nginx-agent-2.21.0~jammy_amd64.deb
./build/github/packages/nginx-agent-2.21.0-v3.16-x86_64.apk

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING document
• If applicable, I have added tests that prove my fix is effective or that my feature works
• If applicable, I have checked that any relevant tests pass after adding my changes
• I have updated any relevant documentation (README.md)

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