fix: tinygo complains about using go 1.21.

Tinygo build fails because we are using go 1.21. But it required go
version 1.20. This commits updates the go version in use

Signed-off-by: José Guilherme Vanz <jguilhermevanz@suse.com>

go.mod

@@ -1,6 +1,6 @@
 module github.com/kubewarden/container-resources-policy
 
-go 1.21
+go 1.20
 
 require (
 	github.com/francoispqt/onelog v0.0.0-20190306043706-8c2bb31b10a4

go.sum

@@ -10,10 +10,6 @@ github.com/google/gofuzz v1.2.0 h1:xRy4A+RhZaiKjJ1bPfwQ8sedCA+YS2YcCHW6ec7JMi0=
 github.com/google/gofuzz v1.2.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
 github.com/kubewarden/k8s-objects v1.29.0-kw1 h1:bVQ2WL1ROqApYmHQJ/yxrs3tssfzzalblE2txChcHxY=
 github.com/kubewarden/k8s-objects v1.29.0-kw1/go.mod h1:EMF+Hr26oDR4yQkWJAQpl0M0Ek5ioNXlCswjGZO0G2U=
-github.com/kubewarden/policy-sdk-go v0.6.1 h1:MNCwo9tZ2lmumv/7/0h7NczwHlazueSnAJYQEmtDApk=
-github.com/kubewarden/policy-sdk-go v0.6.1/go.mod h1:wq/jwnVOpSaETu/n9DW0ePbeoUdoqYTEzlNKmZGaPIM=
-github.com/kubewarden/policy-sdk-go v0.7.0 h1:quNOrqtZRgLHpknoIWl0yDWDK8xJ/hDtP8M40HVDPmc=
-github.com/kubewarden/policy-sdk-go v0.7.0/go.mod h1:wq/jwnVOpSaETu/n9DW0ePbeoUdoqYTEzlNKmZGaPIM=
 github.com/kubewarden/policy-sdk-go v0.8.0 h1:4SR6UeKLBQ+UkwohuMqYw2lPKgqgF5Ifdw7tFNjQwiI=
 github.com/kubewarden/policy-sdk-go v0.8.0/go.mod h1:gjYdcErABXti/dxoNW2PceSwy4+/X+o/wuLwWHZCoNU=
 github.com/kubewarden/strfmt v0.1.3 h1:bb+2rbotioROjCkziSt+hqnHXzOlumN94NxDKdV2kPI=