Merge pull request #1338 from mapproxy/6.0.1

dev: prepare 6.0.1 release

Merge pull request #1327 from simonseyock/6.0.0

dev: prepare 6.0.0 release

Merge pull request #1291 from simonseyock/5.1.1

dev: prepare 5.1.1 release

Merge pull request #1288 from simonseyock/5.1.0

dev: prepare 5.1.0 release

Merge pull request #1181 from simonseyock/5.0.0

dev: prepare 5.0.0 release

Merge pull request #1151 from simonseyock/4.1.2

dev: prepare 4.1.2 release

Merge pull request #1127 from simonseyock/4.1.1

dev: prepare 4.1.1 release

Merge pull request #1122 from simonseyock/4.1.0

dev: prepare 4.1.0 release

Merge pull request #1102 from simonseyock/security-fixes

Security fixes

Merge pull request #1103 from simonseyock/security-fixes-3.x.x

Security fixes 3.x.x