Use dev as development version

Since we're no longer running from `master` branch
It is more fitting to rename it to either dev or
main. This version is only used when running from
source when the CURA_VERSION variable isn't set
while performing the `conan install`

Contributes to CURA-9365

conandata.yml

@@ -1,4 +1,4 @@
-"main":
+"dev":
   git:
     fdm_materials:
       url: "https://github.com/Ultimaker/fdm_materials.git"

conanfile.py

@@ -52,7 +52,7 @@ class CuraConan(ConanFile):
             if "CURA_VERSION" in os.environ:
                 self.version = os.environ["CURA_VERSION"]
             else:
-                self.version = "main"
+                self.version = "dev"
 
     @property
     def _staging(self):
@@ -93,7 +93,7 @@ class CuraConan(ConanFile):
 
     def validate(self):
         if self.version:
-            if self.version != "main" and tools.Version(self.version) <= tools.Version("4"):
+            if self.version != "dev" and tools.Version(self.version) <= tools.Version("4"):
                 raise ConanInvalidConfiguration("Only versions 5+ are support")
 
     def requirements(self):

cura/ApplicationMetadata.py

@@ -6,7 +6,7 @@
 # ---------
 DEFAULT_CURA_APP_NAME = "cura"
 DEFAULT_CURA_DISPLAY_NAME = "Ultimaker Cura"
-DEFAULT_CURA_VERSION = "master"
+DEFAULT_CURA_VERSION = "dev"
 DEFAULT_CURA_BUILD_TYPE = ""
 DEFAULT_CURA_DEBUG_MODE = False
 

cura/Backups/Backup.py

@@ -136,7 +136,7 @@ class Backup:
             return False
 
         current_version = Version(self._application.getVersion())
-        version_to_restore = Version(self.meta_data.get("cura_release", "master"))
+        version_to_restore = Version(self.meta_data.get("cura_release", "dev"))
 
         if current_version < version_to_restore:
             # Cannot restore version newer than current because settings might have changed.