fix: add GOPRIVATE and git config for private module access (#46)

## Summary
- Add `GOPRIVATE=github.com/conductorone/*` env var to lint and test
jobs
- Add optional `RELENG_GITHUB_TOKEN` secret for authenticating to
private repos
- Configure git credentials only when token is provided

## Problem
golangci-lint fails on baton-http based connectors because it can't
access the private `baton-http` module during type checking:

```
could not import github.com/conductorone/baton-http/pkg/bconfig
fatal: could not read Username for 'https://github.com': terminal prompts disabled
```

## Solution
Callers explicitly pass `RELENG_GITHUB_TOKEN` secret, which is used to
configure git credentials for private module access.

## Affected repos (36 total)
All connectors using `template: baton-http-template`

## Tested
- ✅ baton-sagehr PR #61 - both lint and test pass with this fix

## Caller workflow change required
Callers need to pass `RELENG_GITHUB_TOKEN`:

```yaml
jobs:
  verify:
    uses: ConductorOne/github-workflows/.github/workflows/verify.yaml@v4
    with:
      ref: ${{ github.event.pull_request.head.sha || github.sha }}
    secrets:
      RELENG_GITHUB_TOKEN: ${{ secrets.RELENG_GITHUB_TOKEN }}
```

Author: gontzess

.github/workflows/verify.yaml

@@ -8,9 +8,14 @@ on:
         required: false
         type: boolean
         default: true
+    secrets:
+      RELENG_GITHUB_TOKEN:
+        required: false
 jobs:
   lint:
     runs-on: ubuntu-latest
+    env:
+      GOPRIVATE: github.com/conductorone/*
     steps:
     - name: Checkout caller repo
       uses: actions/checkout@v5
@@ -19,6 +24,13 @@ jobs:
         repository: ${{ github.event.repository.full_name }}
         fetch-depth: 0
         ref: ${{ inputs.ref }}
+    - name: Configure git for private modules
+      env:
+        TOKEN: ${{ secrets.RELENG_GITHUB_TOKEN }}
+      run: |
+        if [ -n "$TOKEN" ]; then
+          git config --global url."https://${TOKEN}@github.com/".insteadOf "https://github.com/"
+        fi
     - name: Install Go
       uses: actions/setup-go@v5
       with:
@@ -35,13 +47,22 @@ jobs:
       matrix:
         platform: [ubuntu-latest]
     runs-on: ${{ matrix.platform }}
+    env:
+      GOPRIVATE: github.com/conductorone/*
     steps:
       - name: Checkout caller repo
         uses: actions/checkout@v5
         with:
           repository: ${{ github.event.repository.full_name }}
           fetch-depth: 0
           ref: ${{ inputs.ref }}
+      - name: Configure git for private modules
+        env:
+          TOKEN: ${{ secrets.RELENG_GITHUB_TOKEN }}
+        run: |
+          if [ -n "$TOKEN" ]; then
+            git config --global url."https://${TOKEN}@github.com/".insteadOf "https://github.com/"
+          fi
       - name: Install Go
         uses: actions/setup-go@v5
         with:
@@ -53,4 +74,3 @@ jobs:
         uses: guyarb/golang-test-annotations@v0.8.0
         with:
           test-results: test.json
-