replace deprecated ioutil package functions with latest advised io and os package replacements

[mrutkows]

With the advent of v1.19, we now have a mature replacement for all needed functions from the deprecated ioutil package (as of v1.16).

For example, the utility currently uses ioutil.ReadAll which would be replaced by io.ReadAll.

For a more complete set of package/function mappings see this answer: https://stackoverflow.com/questions/75206234/for-go-ioutil-readall-ioutil-readfile-ioutil-readdir-deprecated

[ajistrying]

Hello there! Is this project open to a golang newbie, if so I'd love to take this one as a first issue and continue to contribute as I learn more 🙂

[mrutkows]

@ajistrying I would welcome any help with the "good first issue" tag and offer time to help, discuss approaches (if not obvious) and provided review/comment on draft PRs.

Please know I have changed a couple of these as part of PR: #40 (which I plan to merge by EOD Monday), but have made no attempt at universally replacing all occurrences.

[ajistrying]

@mrutkows No worries and thank you! What I can do is start on the replacements and wait for that PR to get merged in to incorporate it 👍

[mrutkows]

It appears that these files/occurrences (may) still need refactoring:

$ grep -inr "ioutil" --include=*.go
./cmd/license_policy_config.go:23:	"io/ioutil"
./cmd/license_policy_config.go:176:	buffer, errRead := ioutil.ReadFile(config.policyConfigFile)
./schema/schema_custom_validation.go:23:	"io/ioutil"
./schema/schema_custom_validation.go:48:	buffer, err := ioutil.ReadFile(cfgFilename)
./schema/schema_formats.go:23:	"io/ioutil"
./schema/schema_formats.go:200:	buffer, err := ioutil.ReadFile(cfgFilename)
./schema/schema_formats.go:359:	sbom.rawBytes, errReadAll = ioutil.ReadAll(jsonFile)

[mrutkows]

@ajistrying was wondering if you have time to do this work in the next day or so as I want to rush a release in order to support the latest CycloneDX v1.5 release which happened yesterday. If you are too busy, I may fix the remaining deprecated occurrences just to get them into this release. Sorry, to ask this of you.

[ajistrying]

@mrutkows Yes I definitely can get this done by tomorrow. The start of this week has been pretty busy so apologies!

[mrutkows]

@ajistrying Thanks. I will keep looking for your PR to be submitted and if it looks good create a release after merging it.

[ajistrying]

Just signing off for work, will push up something in the next hour or so!

[ajistrying]

@mrutkows #44 is up! Would love some insight on the automated comments from the sonatype-lift bot on the potential issues it highlighted.

[mrutkows]

Fixed by: #44