Bump OTel SDK/API to 1.6.0

[Kielek]

Fixes N/A.

Changes

Bump OTel SDK/API to 1.6.0
Exporter.Geneva statys on 1.6.0-rc.1 as it depends on non-stable features.

For significant contributions please make sure you have completed the following items:

• Appropriate CHANGELOG.md updated for non-trivial changes
• [ ] Design discussion issue #
• [ ] Changes in public API reviewed

[codecov]

Codecov Report

Merging #1344 (3bbe3c9) into main (75d7622) will increase coverage by 0.01%.
Report is 2 commits behind head on main.
The diff coverage is 50.00%.

❗ Current head 3bbe3c9 differs from pull request most recent head 61e461b. Consider uploading reports for the commit 61e461b to get more accurate results

@@            Coverage Diff             @@
##             main    #1344      +/-   ##
==========================================
+ Coverage   74.49%   74.50%   +0.01%     
==========================================
  Files         266      266              
  Lines        9659     9657       -2     
==========================================
  Hits         7195     7195              
+ Misses       2464     2462       -2     

Files Changed	Coverage
...lemetry.Sampler.AWS/AWSXRayRemoteSamplerBuilder.cs	0.00%
...c/OpenTelemetry.Sampler.AWS/SamplingRuleApplier.cs	100.00%