Replace all buster images with kaniko one

.gitlab-ci.yml

@@ -137,7 +137,7 @@ debian-hardened:
 #####
 # Distcheck on debian stable
 debian-distcheck:
-  image: debian:buster
+  image: gktpo/geko:oldstable
   <<: *debian-template
   variables:
     DISTCHECK: "yes"
@@ -148,7 +148,7 @@ debian-distcheck:
 #####
 # Documentation tests on debian stable: doxygen and asciidoc.
 debian-docs:
-  image: debian:buster
+  image: gktpo/geko:oldstable
   <<: *debian-template
   variables:
     DOXYGEN: "yes"
@@ -166,7 +166,7 @@ debian-docs:
 #       with the 'artifacts' mechanism, in theory, but it would be good to
 #       avoid having to have a system with hundreds of artifacts.
 debian-integration:
-  image: debian:buster
+  image: gktpo/geko:oldstable
   <<: *debian-template
   variables:
     CHECK: "no"
@@ -180,7 +180,7 @@ debian-integration:
 #####
 # Tracing build on Debian stable.
 debian-tracing:
-  image: debian:buster
+  image: gktpo/geko:oldstable
   <<: *debian-template
   variables:
     TRACING: "yes"
@@ -192,7 +192,7 @@ debian-tracing:
 #####
 # No-authority mode
 debian-disable-dirauth:
-  image: debian:buster
+  image: gktpo/geko:oldstable
   <<: *debian-template
   variables:
     DISABLE_DIRAUTH: "yes"
@@ -202,7 +202,7 @@ debian-disable-dirauth:
 #####
 # No-relay mode
 debian-disable-relay:
-  image: debian:buster
+  image: gktpo/geko:oldstable
   <<: *debian-template
   variables:
     DISABLE_RELAY: "yes"
@@ -212,7 +212,7 @@ debian-disable-relay:
 #####
 # NSS check on debian
 debian-nss:
-  image: debian:buster
+  image: gktpo/geko:oldstable
   <<: *debian-template
   variables:
     NSS: "yes"