test: increasing unit test coverage to 90 percent

[mgama-deepgram]

• Increases unit test coverage close to 90 percent (line rate increased from 54% to 95%, and branch rate from 32% to 92%)
• Adding code coverage processes on the CI.yml workflow on the test job
• The test job in the CI.yml workflow will now post the calculated code coverage as a PR comment
• Replaces original PR that only included changes to ci.yml workflow docs: adding code coverage processes on ci.yml workflow #735

[github-actions]

Package	Line Rate	Branch Rate	Complexity	Health
src.deepgram	95%	88%	0	✔
src.deepgram.agent	100%	100%	0	✔
src.deepgram.agent.v1	94%	97%	0	✔
src.deepgram.agent.v1.settings	100%	100%	0	✔
src.deepgram.agent.v1.settings.think	100%	100%	0	✔
src.deepgram.agent.v1.settings.think.models	97%	100%	0	✔
src.deepgram.auth	100%	100%	0	✔
src.deepgram.auth.v1	100%	100%	0	✔
src.deepgram.auth.v1.tokens	97%	100%	0	✔
src.deepgram.core	90%	84%	0	➖
src.deepgram.errors	100%	100%	0	✔
src.deepgram.helpers	100%	95%	0	✔
src.deepgram.listen	100%	100%	0	✔
src.deepgram.listen.v1	94%	93%	0	✔
src.deepgram.listen.v1.media	97%	100%	0	✔
src.deepgram.listen.v2	93%	89%	0	✔
src.deepgram.manage	100%	100%	0	✔
src.deepgram.manage.v1	100%	100%	0	✔
src.deepgram.manage.v1.models	96%	100%	0	✔
src.deepgram.manage.v1.projects	97%	100%	0	✔
src.deepgram.manage.v1.projects.billing	100%	100%	0	✔
src.deepgram.manage.v1.projects.billing.balances	96%	100%	0	✔
src.deepgram.manage.v1.projects.billing.breakdown	97%	100%	0	✔
src.deepgram.manage.v1.projects.billing.fields	97%	100%	0	✔
src.deepgram.manage.v1.projects.billing.purchases	97%	100%	0	✔
src.deepgram.manage.v1.projects.keys	96%	100%	0	✔
src.deepgram.manage.v1.projects.members	97%	100%	0	✔
src.deepgram.manage.v1.projects.members.invites	96%	100%	0	✔
src.deepgram.manage.v1.projects.members.scopes	96%	100%	0	✔
src.deepgram.manage.v1.projects.models	96%	100%	0	✔
src.deepgram.manage.v1.projects.usage	98%	100%	0	✔
src.deepgram.manage.v1.projects.usage.breakdown	97%	100%	0	✔
src.deepgram.manage.v1.projects.usage.fields	97%	100%	0	✔
src.deepgram.read	100%	100%	0	✔
src.deepgram.read.v1	100%	100%	0	✔
src.deepgram.read.v1.text	98%	100%	0	✔
src.deepgram.self_hosted	100%	100%	0	✔
src.deepgram.self_hosted.v1	100%	100%	0	✔
src.deepgram.self_hosted.v1.distribution_credentials	96%	100%	0	✔
src.deepgram.speak	100%	100%	0	✔
src.deepgram.speak.v1	94%	93%	0	✔
src.deepgram.speak.v1.audio	91%	80%	0	✔
src.deepgram.voice_agent	100%	100%	0	✔
src.deepgram.voice_agent.configurations	95%	100%	0	✔
src.deepgram.voice_agent.variables	95%	100%	0	✔
Summary	95% (5954 / 6273)	92% (1276 / 1386)	0	✔