drop support of older versions of Coq and ssreflect

Coq 8.11, Coq 8.12, ssreflect 1.10, and ssreflect 1.11
are no longer supported

.gitlab-ci.yml

@@ -93,21 +93,6 @@ stages:
 
 ###################### The Jobs ######################
 
-1.10.0-coq-8.11:
-  extends:
-    - .build
-    - .not_in_wip_branches
-
-1.11.0-coq-8.11:
-  extends:
-    - .build
-    - .not_in_wip_branches
-
-1.11.0-coq-8.12:
-  extends:
-    - .build
-    - .not_in_wip_branches
-
 1.12.0-coq-8.13:
   extends:
     - .build

coq-prosa.opam

@@ -13,8 +13,8 @@ build: [
 ]
 install: [make "install"]
 depends: [
-  "coq" {((>= "8.11" & < "8.14~") | = "dev")}
-  "coq-mathcomp-ssreflect" {((>= "1.10" & < "1.13~") | = "dev")}
+  "coq" {((>= "8.13" & < "8.14~") | = "dev")}
+  "coq-mathcomp-ssreflect" {((>= "1.12" & < "1.13~") | = "dev")}
 ]
 
 tags: [