Release 2020.3

A quick followup to 2020.2, which introduced support
for [read-only sysroot][1] ended up breaking some of
the Fedora CoreOS tests in [coreos-assembler][2]
which in turn holds back ostree going into FCOS:
https://github.com/coreos/fedora-coreos-tracker/issues/343

Now we've closed that gap and are running more of those
tests as part of our [new CI][3].

[1] https://github.com/ostreedev/ostree/pull/1767/commits/5af403be0cc64df50ad21cef05f3268ead256d6d
[2] https://github.com/coreos/fedora-coreos-tracker/issues/343
[3] https://github.com/coreos/fedora-coreos-tracker/issues/263

```
Colin Walters (3):
      Post-release version bump
      ci: Test kola --upgrades
      main: Also automatically remount rw /sysroot for `ostree pull` etc.

Jonathan Lebon (3):
      ci: migrate to new coreos-ci project
      ci: use `fcosKola` for running kola tests
      Release 2020.3
```

Git-EVTag-v0-SHA512: 0032a560965e0dc2e8cd27b4324b54ca5f968a0a1f2ca67f1de7d810ac135595c034f3f5d2f8f68ef38cb0172558d0911583cd57c17cf12b1cba19ebdadf8997
-----BEGIN PGP SIGNATURE-----

iQFHBAABCgAxFiEEq5KKnPjdBikJw3u93EX9WSHBPwsFAl5s+PUTHHdhbHRlcnNA
dmVyYnVtLm9yZwAKCRDcRf1ZIcE/C7lyCACWIQxXkaLh1Ur5FT2n9fgrMokHTUU0
yslEXii24668eJfb9DgYTSaH5pm6XhDch/gJ7UVQWiJICWXXco6XUiBoVsmkgwBA
/vgjD986+WZqcGqEIA18RxKi1fWr5IDEPC6al8JruOnQeuMlMAluibuCG6WcE38r
PP5uoQk0P+9UZx0GFqbxWlmLnjzLP2XCa/VPV1YGy+RE6piWcEn97Lur2klKdlFz
SoHhgP7QBoi/PkhmBeLeLsqutX8/PnJfuqgKn6MMp9g2AJ/gRcictv2Qud4mkcLG
iQ4TVY29MFTYy/rvAp/ZHweTNfH1IPzn7/8lkHK+fmmzjXfGFlWO0c34
=57pZ
-----END PGP SIGNATURE-----