fix: Add correct project reference in IncidentBot to fix builds

[alexpls]

Updates the Sample.Common.Beta project reference to match the project that has been added to the IncidentBot solution. This gets the solution building again, without it this error is thrown during build:

Severity	Code	Description	Project	File	Line	Suppression State
Error	NU1105	Unable to find project information for 'C:\Users\alexp\Source\Repos\microsoft-graph-comms-samples\Samples\Common\Sample.Common\Sample.Common.csproj'. If you are using Visual Studio, this may be because the project is unloaded or not part of the current solution so run a restore from the command-line. Otherwise, the project file may be invalid or missing targets required for restore.	IncidentBot	C:\Users\alexp\Source\Repos\microsoft-graph-comms-samples\Samples\V1.0Samples\RemoteMediaSamples\IncidentBot\IncidentBot.csproj	1	

Note the Sample.Common.Beta project uses beta versions of the Microsoft Graph API (1.2.0-beta.1) which are now outdated. This PR is just around making the smallest change possible to get IncidentBot building, so I figure updating the dependencies is out of scope.

[msftclas]

All CLA requirements met.

[alexpls]

Closing as the changes in this PR have now been added to master as part of #202