fix(deps): update dependency postmark to v4

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
postmark (source)	2.9.5 -> 4.0.5

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Release Notes

ActiveCampaign/postmark.js (postmark)

v4.0.5

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• update axios to 1.7.4

v4.0.4

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• update axios to 1.7.2

v4.0.3

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• updated models to support adding content disposition to attachments
• update domain model

v4.0.2

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• updated models to be more accurate mostly within webhook payloads area

v4.0.1

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• update development libraries

v4.0.0

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• dropped support for older EOL Node JS versions, minimum supported Node version is 14.0.0
• updated axios to the version 1.6.2

v3.11.0

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• added filtering to get suppressions endpoint

v3.1.2

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• add content type header to the http client default headers list

v3.1.1

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• small naming update for data removal endpoints

v3.1.0

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• added data removal endpoints

v3.0.20

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• small fix to webhook types model

v3.0.19

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• updated model to contain webhook types

v3.0.18

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• fix domain endpoint request types

v3.0.17

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• updated test library versions
• switched from nconf to dotenv for configuration loading for tests

v3.0.16

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v3.0.15

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• added Sanboxed field to the outbound message model
• fix parsing bounced messages

v3.0.14

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• Updated statistics filtering parameter

v3.0.13

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• Minor code fix, fixing up library versions for older versions of node

v3.0.12

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• Migrated to ActiveCampaign

v3.0.11

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• Small bug fix to data model

v3.0.1

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• updated model to contain webhook types

v3.0.0

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• Updated message response for sending
• Decoupled and refactored http client part of the library

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