Bugfixes in testing. Fix warnings due to changes in {rgdal} and PROJ6.

5 jobs for master in 5 minutes and 51 seconds (queued for 2 seconds)
Name Stage Failure
failed
test-devel Test
6. Error: Missing CRS in epidemiological units (@test-risk_unit.R#58) 
7. Failure: Polygons not covering any raster-cell center (@test-risk_unit.R#84)
8. Failure: Polygons not covering any raster-cell center (@test-risk_unit.R#87)

Error: testthat unit tests failed
Execution halted
Execution halted
Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1

failed
test-release Test
6. Error: Missing CRS in epidemiological units (@test-risk_unit.R#58) 
7. Failure: Polygons not covering any raster-cell center (@test-risk_unit.R#84)
8. Failure: Polygons not covering any raster-cell center (@test-risk_unit.R#87)

Error: testthat unit tests failed
Execution halted
Execution halted
Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1

failed
test-oldrel Test
6. Error: Missing CRS in epidemiological units (@test-risk_unit.R#58) 
7. Failure: Polygons not covering any raster-cell center (@test-risk_unit.R#84)
8. Failure: Polygons not covering any raster-cell center (@test-risk_unit.R#87)

Error: testthat unit tests failed
Execution halted
Execution halted
Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1