blob/azblob: Fix azure-storage-blob-go checksum

[stanhu]

The tag for this module got yanked and now checksums are failing. Pin
the version to the pseudo-version as described in
Azure/azure-storage-blob-go#236 (comment).

[codecov]

Codecov Report

Merging #2935 (2f9beec) into master (48f2d4c) will increase coverage by 0.11%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #2935      +/-   ##
==========================================
+ Coverage   69.17%   69.28%   +0.11%     
==========================================
  Files         110      110              
  Lines       11451    11451              
==========================================
+ Hits         7921     7934      +13     
+ Misses       2882     2868      -14     
- Partials      648      649       +1     

Impacted Files	Coverage Δ
blob/s3blob/s3blob.go	89.47% <0.00%> (+0.52%)	⬆️
pubsub/rabbitpubsub/rabbit.go	80.68% <0.00%> (+0.75%)	⬆️
internal/retry/retry.go	100.00% <0.00%> (+7.69%)	⬆️
server/health/sqlhealth/sqlhealth.go	78.37% <0.00%> (+21.62%)	⬆️

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[stanhu]

@vangent Would you mind merging this? I'm blocked on upgrading go-cloud due to this dependency issue.