Fix the codemeta.json file

HAL's metadata export function doesn't seem to respect the CodeMeta
v2.0 format.

codemeta.json

 {
     "@context": [
-        "https:\/\/doi.org\/doi:10.5063\/schema\/codemeta-2.0",
-        "http:\/\/schema.org"
+        "https:\/\/doi.org\/10.5063\/schema\/codemeta-2.0"
     ],
     "@type": "SoftwareSourceCode",
     "name": "digger",
@@ -9,7 +8,7 @@
     "dateCreated": "2016-10-03",
     "datePublished": "2024-01-30",
     "license": [
-        "CeCILL Free Software License Agreement v2.1"
+        "https://spdx.org/licenses/CECILL-2.1"
     ],
     "url": "https:\/\/hal.science\/hal-04427164",
     "identifier": [],
@@ -22,10 +21,6 @@
         "Security",
         "Formal Methods"
     ],
-    "institution": [
-        "Universit\u00e9 de Lille",
-        "CNRS"
-    ],
     "codeRepository": "https:\/\/github.com\/2xs\/digger",
     "relatedLink": [
         "https:\/\/github.com\/2xs\/pipcore",
@@ -52,11 +47,7 @@
     "developmentStatus": "Inactif",
     "author": [
         {
-            "@type": "Role",
-            "roleName": "architecture",
-            "author": {
             "@type": "Person",
-                "@id": null,
             "givenName": "Gilles",
             "familyName": "Grimaud",
             "affiliation": [
@@ -65,14 +56,9 @@
                     "name": "CRIStAL"
                 }
             ]
-            }
         },
         {
-            "@type": "Role",
-            "roleName": "aut",
-            "author": {
             "@type": "Person",
-                "@id": null,
             "givenName": "Samuel",
             "familyName": "Hym",
             "affiliation": [
@@ -81,14 +67,9 @@
                     "name": "CRIStAL"
                 }
             ]
-            }
         },
         {
-            "@type": "Role",
-            "roleName": "aut",
-            "author": {
             "@type": "Person",
-                "@id": null,
             "givenName": "Ve\u00efs",
             "familyName": "Oudjail",
             "affiliation": [
@@ -97,6 +78,5 @@
                 }
             ]
         }
-        }
     ]
 }