Add Go 1.18 to compatibility tested versions

[MrAlias]

Fix #1975

golang.org/x/sys is upgraded to latest to resolve the issue identified here: golang/go#49219

[codecov]

Codecov Report

Merging #1976 (d6f2b9d) into main (5eecde7) will increase coverage by 3.8%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##            main   #1976     +/-   ##
=======================================
+ Coverage   72.1%   76.0%   +3.8%     
=======================================
  Files        124     126      +2     
  Lines       5330    5376     +46     
=======================================
+ Hits        3848    4089    +241     
+ Misses      1370    1162    -208     
- Partials     112     125     +13     

Impacted Files	Coverage Δ
...n/github.com/gocql/gocql/otelgocql/test/version.go	0.0% <0.0%> (ø)
.../github.com/gocql/gocql/otelgocql/internal/cass.go	95.1% <0.0%> (ø)
...ion/github.com/gocql/gocql/otelgocql/instrument.go	62.5% <0.0%> (+62.5%)	⬆️
...ntation/github.com/gocql/gocql/otelgocql/config.go	67.3% <0.0%> (+67.3%)	⬆️
...ation/github.com/gocql/gocql/otelgocql/observer.go	75.1% <0.0%> (+75.1%)	⬆️
...entation/github.com/gocql/gocql/otelgocql/gocql.go	100.0% <0.0%> (+100.0%)	⬆️
...tation/github.com/gocql/gocql/otelgocql/version.go	100.0% <0.0%> (+100.0%)	⬆️