fix: add missing license headers

[jasminetMSFT]

This PR will fix the missing license headers mentioned in #435 using the skywalking-eyes fix header tool.
Header check result is shown as follows:

INFO Loading configuration from file: .licenserc.yaml
INFO Totally checked 730 files, valid: 38, invalid: 14, ignored: 678, fixed: 0
INFO GITHUB_TOKEN is not set, license-eye won't comment on the pull request
ERROR the following files don't have a valid license header:
.github/.codecov.yml
.github/dependabot.yml
.github/workflows/build.yml
.github/workflows/codeql-analysis.yml
.github/workflows/release-ghcr.yml
.github/workflows/release-github.yml
.gitignore
.goreleaser.yml
Dockerfile
Makefile
cmd/oras/main.go
cmd/oras/version.go
internal/credential/store.go
internal/version/version.go
ERROR one or more files does not have a valid license header

Signed-off-by: JasmineTang [email protected]

[codecov-commenter]

Codecov Report

Merging #545 (25ed1b6) into main (45a1024) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #545   +/-   ##
=======================================
  Coverage   70.78%   70.78%           
=======================================
  Files          11       11           
  Lines         421      421           
=======================================
  Hits          298      298           
  Misses        100      100           
  Partials       23       23           

Impacted Files	Coverage Δ
internal/credential/store.go	65.75% <ø> (ø)

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[shizhMSFT]

LGTM