Add 'Z' to tx timestamps to tell client that it's UTC

[kylanhurt]

Fixes #707

Description

• TX timestamp showing incorrect because block timestamps do not have the 'Z' indicating the UTC time zone. They are not ISO-compliant 👎 but since they always do not have the 'Z' then we can just manually add it

Test scenarios

Time now matches the timestamp on the homepage

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have cleaned up the code in the areas my change touches
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules
• I have checked my code and corrected any misspellings
• I have removed any unnecessary console messages
• I have included all english text to the translation file and/or created a new issue with the required translations for the currently supported languages
• I have tested for mobile functionality and responsiveness
• I have added appropriate test coverage

[netlify]

✅ Deploy Preview for obe-testnet ready!

Name	Link
🔨 Latest commit	332798f
🔍 Latest deploy log	https://app.netlify.com/sites/obe-testnet/deploys/6531783ed513ed00083c1a4d
😎 Deploy Preview	https://deploy-preview-790--obe-testnet.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[netlify]

✅ Deploy Preview for obe-staging ready!

Name	Link
🔨 Latest commit	332798f
🔍 Latest deploy log	https://app.netlify.com/sites/obe-staging/deploys/6531783ea5df0f00083ac5ca
😎 Deploy Preview	https://deploy-preview-790--obe-staging.netlify.app/
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.