Create version 0.4.3

[simonschoelly]

In response to #121 we should have a new version that adds the latest changes. Therefore this PR does:

• Bump version to 0.4.3
• Add Julia 1.5 to testing pipeline
• Set min Julia version to 1.3 - with 1.0 there where some problems running tests with Cairo

[codecov]

Codecov Report

Merging #122 into master will not change coverage.
The diff coverage is n/a.

@@ Coverage Diff @@## master #122 +/- ##
=======================================
Coverage 33.20% 33.20% =======================================
Files 9 9 Lines 524 524 =======================================
Hits 174 174 Misses 350 350 

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 692e6e1...36a466b. Read the comment docs.