fix: provide dnf for rpmbuild #377

Job	Run time
prepare	4s
build-apko (./images/git/image.yaml, ghcr.io/geonet/base-images/git:latest)	12s
build-apko (./images/git-ssh/image.yaml, ghcr.io/geonet/base-images/git-ssh:latest)	11s
build-apko (./images/alpine-iputils/image.yaml, ghcr.io/geonet/base-images/alpine-iputils:3.18)	9s
build-apko (./images/alpine-xslt/image.yaml, ghcr.io/geonet/base-images/alpine-xslt:3.18)	9s
build-apko (./images/alpine-gdal/image.yaml, ghcr.io/geonet/base-images/alpine-gdal:3.15)	13s
build-apko (./images/texlive/image.yaml, ghcr.io/geonet/base-images/texlive:latest)	28s
build-docker (./images/chart-centos7/Dockerfile, ghcr.io/geonet/base-images/chart-centos7:latest,... / build	1m 57s
build-docker (./images/mkdocs_plus/Dockerfile, ghcr.io/geonet/base-images/mkdocs_plus:latest, ghc... / build	1m 58s
	5m 21s

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