test: update user-agent in tests to axios/1.15.2 (#1171)

* fix: update user-agent in tests to axios/1.15.2

* test: update test coverage

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: Cafe137

test/regression/bee-js-986.spec.ts

@@ -36,7 +36,7 @@ test('bee-js/986 - Headers not merging properly', async () => {
       'swarm-encrypt': 'true',
       'swarm-postage-batch-id': Types.asString(process.env.JEST_MANAGED_BATCH_ID),
       'swarm-tag': '1337',
-      'user-agent': 'axios/1.15.1',
+      'user-agent': 'axios/1.15.2',
     },
     method: 'POST',
     url: '/bzz?name=filename.txt',
@@ -54,7 +54,7 @@ test('bee-js/986 - Headers not merging properly', async () => {
       'swarm-encrypt': 'true',
       'swarm-postage-batch-id': Types.asString(process.env.JEST_MANAGED_BATCH_ID),
       'swarm-tag': '1338',
-      'user-agent': 'axios/1.15.1',
+      'user-agent': 'axios/1.15.2',
     },
     method: 'POST',
     url: '/bzz?name=filename.txt',