Update download page to force a Tails Verification version that checks the amd64 IDF

Originally created by @sajolida on #12496 (Redmine)

Once we have #12494 (closed), we should update the <div id="extension-version"> on install/inc/steps/download.inline.html to force using the new version of DAVE that checks the amd64 IDF.

Related issues

Blocked by #12494 (closed)
Blocks #14758 (closed)

Edited May 15, 2020 by sajolida

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