Add --network=host to validatepr container for GitHub access

[Honny1]

Allows the validatepr container to fetch dependencies from GitHub during validation by enabling host networking.

This PR fixes the error of make validatepr on macOS:

...
+ echo 'Running validation tooling'
Running validation tooling
++ awk '/MemTotal/ {print $2}' /proc/meminfo
+ mem=5009584
+ ((  5009584 < 3900000  ))
+ make validate
make[1]: Entering directory '/go/src/github.com/containers/podman'
VERSION=2.6.0 ./hack/install_golangci.sh
Installing golangci-lint v2.6.0 into ./bin/golangci-lint
golangci/golangci-lint info checking GitHub for tag 'v2.6.0'
golangci/golangci-lint info found version: 2.6.0 for v2.6.0/linux/arm64
golangci/golangci-lint info installed ./bin/golangci-lint
hack/golangci-lint.sh
Linting for GOOS=linux
+ ./bin/golangci-lint run --build-tags=apparmor,seccomp,selinux
pkg/selinux/selinux.go:4:2: could not import github.com/opencontainers/selinux/go-selinux (/root/go/pkg/mod/go.podman.io/storage@v1.61.1-0.20251112195944-4afce3558e66/layers.go:22:2: reading github.com/opencontainers/selinux/go.mod at revision v1.13.1: git ls-remote -q origin in /root/go/pkg/mod/cache/vcs/49bf5caa92b4f9ff8c1e2713127b5413597f3869c253c1159d7d4bf7be68beab: exit status 128:
	fatal: unable to access 'https://github.com/opencontainers/selinux/': Failed to connect to github.com port 443 after 1015 ms: Could not connect to server) (typecheck)
	"github.com/opencontainers/selinux/go-selinux"
	^
pkg/selinux/selinux.go:13:21: undefined: selinux (typecheck)
	processLabel, _ := selinux.KVMContainerLabels()
	                   ^
pkg/selinux/selinux.go:14:2: undefined: selinux (typecheck)
	selinux.ReleaseLabel(processLabel)
	^
pkg/selinux/selinux.go:24:21: undefined: selinux (typecheck)
	processLabel, _ := selinux.InitContainerLabels()
	                   ^
pkg/selinux/selinux.go:25:2: undefined: selinux (typecheck)
	selinux.ReleaseLabel(processLabel)
	^
pkg/selinux/selinux.go:30:15: undefined: selinux (typecheck)
	dcon, err := selinux.NewContext(cLabel)
	             ^
pkg/selinux/selinux.go:34:15: undefined: selinux (typecheck)
	scon, err := selinux.NewContext(processLabel)
	             ^
7 issues:
* typecheck: 7
make[1]: *** [Makefile:291: golangci-lint] Error 1
make[1]: Leaving directory '/go/src/github.com/containers/podman'
make: *** [Makefile:345: .validatepr] Error 2
gmake: *** [Makefile:335: validatepr] Error 2

Checklist

Ensure you have completed the following checklist for your pull request to be reviewed:

• Certify you wrote the patch or otherwise have the right to pass it on as an open-source patch by signing all
  commits. (git commit -s). (If needed, use git commit -s --amend). The author email must match
  the sign-off email address. See CONTRIBUTING.md
  for more information.
• Referenced issues using Fixes: #00000 in commit message (if applicable)
• Tests have been added/updated (or no tests are needed)
• Documentation has been updated (or no documentation changes are needed)
• All commits pass make validatepr (format/lint checks)
• Release note entered in the section below (or None if no user-facing changes)

Does this PR introduce a user-facing change?

None

[Honny1]

Unrelated CI failure; fixed in #27562

[baude]

sure, nice add.

LGTM

[Luap99]

/lgtm

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Honny1, Luap99

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