Only run checks on examples with one rust toolchain version

There's no point in running it with two versions, and MSRV should
suffice.

Signed-off-by: Matthias Beyer <[email protected]>

Author: matthiasbeyer

.github/workflows/msrv.yml

@@ -131,7 +131,6 @@ jobs:
       matrix:
         rust:
           - 1.70.0
-          - 1.73.0
 
     steps:
       - name: Checkout sources