Fixed branch header conflits issue

[sunil-lakshman]

let branch = stackHeaders.branch || http.defaults.headers.branch || 'main'

This line resolves branch conflicts by prioritizing the branch value: first from stackHeaders, then from the client's default HTTP headers, and finally defaults to 'main' if neither is set.

[github-actions]

Coverage report for commit: 2745dbe
File: coverage/clover.xml

Cover ┌─────────────────────────┐ Freq.
   0% │ ░░░░░░░░░░░░░░░░░░░░░░░ │  0.0%
  10% │ ░░░░░░░░░░░░░░░░░░░░░░░ │  0.0%
  20% │ ██░░░░░░░░░░░░░░░░░░░░░ │  2.3%
  30% │ ░░░░░░░░░░░░░░░░░░░░░░░ │  0.0%
  40% │ ░░░░░░░░░░░░░░░░░░░░░░░ │  0.0%
  50% │ ░░░░░░░░░░░░░░░░░░░░░░░ │  0.0%
  60% │ ░░░░░░░░░░░░░░░░░░░░░░░ │  0.0%
  70% │ ░░░░░░░░░░░░░░░░░░░░░░░ │  0.0%
  80% │ ██████████░░░░░░░░░░░░░ │ 18.2%
  90% │ ███████████████████████ │ 43.2%
 100% │ ████████████████████░░░ │ 36.4%
      └─────────────────────────┘
 *Legend:* █ = Current Distribution 

Summary - Lines: 88.72% | Methods: 97.67% | Branches: 73.15%

Files	Lines	Methods	Branches
lib
contentstack.js	83.33%	100.00%	84.62%
contentstackClient.js	80.85%	92.86%	64.15%
contentstackCollection.js	94.12%	100.00%	86.67%
entity.js	82.16%	100.00%	65.00%
lib/core
Util.js	96.36%	100.00%	83.64%
concurrency-queue.js	86.01%	87.18%	76.00%
contentstackError.js	100.00%	100.00%	100.00%
contentstackHTTPClient.js	96.77%	100.00%	93.65%
oauthHandler.js	92.54%	100.00%	70.07%
lib/organization
index.js	81.82%	100.00%	60.49%
lib/organization/teams
index.js	92.11%	100.00%	68.42%
lib/organization/teams/stackRoleMappings
index.js	89.29%	100.00%	58.14%
lib/organization/teams/teamUsers
index.js	100.00%	100.00%	93.75%
lib/query
index.js	80.43%	100.00%	67.27%
lib/stack/asset/folders
index.js	100.00%	100.00%	100.00%
lib/stack/asset
index.js	93.06%	100.00%	81.18%
lib/stack/auditlog
index.js	95.83%	100.00%	75.00%
lib/stack/branch
compare.js	81.82%	100.00%	71.88%
index.js	97.44%	100.00%	80.56%
mergeQueue.js	100.00%	100.00%	73.68%
lib/stack/branchAlias
index.js	86.21%	100.00%	65.85%
lib/stack/contentType/entry
index.js	88.39%	100.00%	64.60%
lib/stack/contentType/entry/variants
index.js	86.21%	100.00%	68.57%
lib/stack/contentType
index.js	89.23%	100.00%	74.03%
lib/stack/deliveryToken
index.js	95.24%	80.00%	89.47%
lib/stack/deliveryToken/previewToken
index.js	21.43%	25.00%	14.29%
lib/stack/environment
index.js	100.00%	100.00%	100.00%
lib/stack/extension
index.js	95.92%	100.00%	87.76%
lib/stack/globalField
index.js	94.44%	100.00%	84.31%
lib/stack
index.js	84.43%	92.86%	73.48%
lib/stack/label
index.js	100.00%	100.00%	100.00%
lib/stack/locale
index.js	100.00%	100.00%	100.00%
lib/stack/managementToken
index.js	100.00%	100.00%	94.44%
lib/stack/release
index.js	91.11%	100.00%	72.34%
lib/stack/roles
index.js	100.00%	100.00%	100.00%
lib/stack/taxonomy
index.js	88.00%	100.00%	64.52%
lib/stack/taxonomy/terms
index.js	92.31%	100.00%	72.55%
lib/stack/variantGroup
index.js	86.84%	100.00%	65.12%
lib/stack/variantGroup/variants
index.js	85.00%	100.00%	60.78%
lib/stack/variants
index.js	84.21%	100.00%	59.57%
lib/stack/webhook
index.js	89.66%	100.00%	72.88%
lib/stack/workflow
index.js	89.09%	100.00%	72.31%
lib/stack/workflow/publishRules
index.js	100.00%	100.00%	100.00%
lib/user
index.js	94.29%	100.00%	82.14%

_{🤖 comment via lucassabreu/comment-coverage-clover}

[harshithad0703]

LGTM

[bramski]

This is a public repo. Please write descriptions for the work that's done so external people using can understand what bug you fixed.