fix(repo): update repo urls to `repo.saltproject.io` (inc. fix for `oraclelinux-7`)

[myii]

PR progress checklist (to be filled in by reviewers)

• [ ] Changes to documentation are appropriate (or tick if not required)
• [ ] Changes to tests are appropriate (or tick if not required)
• [ ] Reviews completed

---

What type of PR is this?

Primary type

• [ ] [build] Changes related to the build system
• [ ] [chore] Changes to the build process or auxiliary tools and libraries such as documentation generation
• [ ] [ci] Changes to the continuous integration configuration
• [ ] [feat] A new feature
• [x] [fix] A bug fix
• [ ] [perf] A code change that improves performance
• [ ] [refactor] A code change that neither fixes a bug nor adds a feature
• [ ] [revert] A change used to revert a previous commit
• [ ] [style] Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc.)

Secondary type

• [ ] [docs] Documentation changes
• [ ] [test] Adding missing or correcting existing tests

Does this PR introduce a BREAKING CHANGE?

No.

Related issues and/or pull requests

Describe the changes you're proposing

Use the following command:

$ GREP_SED="\(repo\.salt\)stack\.com" \
  && grep -rl --exclude-dir=.git "${GREP_SED}" \
  | grep -v .un~$ \
  | xargs sed -i -e "/${GREP_SED}/s//\1project.io/g"

The oraclelinux-7 fix is needed to avoid this error:

      ID: salt-master
Function: pkg.installed
  Result: False
 Comment: Error occurred installing package(s). Additional info follows:

   errors:
       - Running scope as unit run-402.scope.
         Loaded plugins: ovl, ulninfo
         https://repo.saltproject.io/py3/redhat/7Server/x86_64/3002/repodata/repomd.xml:
             [Errno 14] HTTPS Error 404 - Not Found
         Trying other mirror.
         No package salt-master available.
         Error: Nothing to do

Pillar / config required to test the proposed changes

Debug log showing how the proposed changes work

Documentation checklist

• [ ] Updated the README (e.g. Available states).
• [ ] Updated pillar.example.

Testing checklist

• [ ] Included in Kitchen (i.e. under state_top).
• [ ] Covered by new/existing tests (e.g. InSpec, Serverspec, etc.).
• [ ] Updated the relevant test pillar.

Additional context

[myii]

Self-merge, fix is needed now because CI is broken.

[saltstack-formulas-travis]

:tada: This PR is included in version 1.8.5 :tada:

The release is available on GitHub release

Your semantic-release bot :package::rocket: