glab api using :branch does not urlencode
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### Checklist
- [x] I'm using the latest version of the extension (Run `glab --version`)
- Extension version: _\`_glab 1.101.0 (b3786045)_\`_
- [x] Operating system and version: _debian 13_
- [x] Gitlab.com or self-managed instance? _gitlab.com_
- [ ] GitLab version (if self-managed) _GitLab version here_ (Use the `version` endpoint, like this: gitlab.my-company.com/api/v4/version)
- [x] I have performed `glab auth status` to check for authentication issues
- [x] Run the command in debug mode (like `DEBUG=true glab mr list`) and attach any useful output
### Summary
When a branch has a `/` in it, glab api does not urlenocde it properly
### Environment
- OS: Linux 6.12.73+deb13-amd64 x86_64
- SHELL: /bin/bash
- TERM: tmux-256color
- GLAB: glab 1.101.0 (b3786045)
### Steps to reproduce
1. create a branch named `test/whatever`
2. setup branch protection (this is just teh api I was using)
3. `glab api /projects/:id/protected_branches/:branch` -\> get 404
4. `glab api /projects/:id/protected_branches/test%2Fwhatever` -\> get data
### What is the current _bug_ behavior?
404
### What is the expected _correct_ behavior?
not 404
### Relevant logs and/or screenshots
```
$ DEBUG=true glab api /projects/:id/protected_branches/:branch
[git remote -v]
[git config --get-regexp ^remote\..*\.glab-resolved(-base|-head)?$]
[git symbolic-ref --quiet --short HEAD]
{
"error": "404 Not Found"
}
glab: HTTP 404
```
### Possible fixes
url encode `:branch`
issue