fix(ci): revise distribution scripts and workflow

[wpbonelli]

• Only trigger job to open PR reinitializing develop after release is published. The automated workflow only creates a draft release — the release must be published manually after inspection. Previously the reinitialization job was triggered immediately after the release branch was merged to master, after this reinit will only happen after the release post is converted from draft to official.

• Update develop reinitialization job such that, for minor version releases, minor version number is incremented from just-released version and patch number is reset to 0, while for patch releases, the version on develop does not change. This is according to the tentative expectation that minor version releases will branch from develop, while patch releases will branch from master to exclude broader changesets in progress on develop. The forthcoming 6.4.1 release is an exception to the above: develop will be bumped to 6.5.0 after 6.4.1 but will then stay there for all subsequent 6.4.X patches until 6.5.0 is released.

• Run test suite after building binaries (tests should all pass before a release branch is created, but a final check is probably not a bad idea)

• Fix test_z01_testmodels_mf6.py to skip dev testmodels/examples on v6* branches, since this is how release branches must be named to trigger the release.yml workflow (previously only skipped on branches named master and release)

• Add developmode test marker to skip tests requiring IDEVELOPMODE = 1 in the release workflow

• Fix update_version.py minor/patch version increment flags

• Only build examples in build_dist.py for full release