Deps: come back to semver ^a.b.c syntax

Thinking about it again, the user-friendlier `a.x` syntax has one disadvantage
over `^a.b.c`: it doesn't force deps upgrades when they upgrade Nativefier.
`a.x` is fine on initial install, but a user with an insecure dep
(e.g. axios 0.19.0) will _not_ get fixed axios 0.21.1 on upgrading Nativefier.
-> Come back to `a.x` everywhere.

Still not introducing package locks, they're too confusing to new devs.
See https://github.com/nativefier/nativefier/pull/1099#issuecomment-761250232

app/package.json

@@ -12,14 +12,14 @@
   ],
   "scripts": {},
   "dependencies": {
-    "electron-context-menu": "2.x",
-    "electron-dl": "3.x",
-    "electron-squirrel-startup": "1.x",
-    "electron-window-state": "5.x",
-    "source-map-support": "0.x",
-    "wurl": "2.x"
+    "electron-context-menu": "^2.5.0",
+    "electron-dl": "^3.1.0",
+    "electron-squirrel-startup": "^1.0.0",
+    "electron-window-state": "^5.0.3",
+    "source-map-support": "^0.5.19",
+    "wurl": "^2.5.4"
   },
   "devDependencies": {
-    "electron": "11.x"
+    "electron": "^11.1.1"
   }
 }

package.json

@@ -54,37 +54,37 @@
   },
   "dependencies": {
     "axios": "^0.21.1",
-    "commander": "4.x",
-    "electron-packager": "15.x",
-    "gitcloud": "0.x",
-    "hasbin": "1.x",
-    "loglevel": "1.x",
-    "ncp": "2.x",
-    "page-icon": "0.x",
-    "sanitize-filename": "1.x",
-    "shelljs": "0.x",
-    "source-map-support": "0.x",
-    "tmp": "0.x"
+    "commander": "^4.1.1",
+    "electron-packager": "^15.2.0",
+    "gitcloud": "^0.1.3",
+    "hasbin": "^1.2.3",
+    "loglevel": "^1.7.1",
+    "ncp": "^2.0.0",
+    "page-icon": "^0.3.4",
+    "sanitize-filename": "^1.6.3",
+    "shelljs": "^0.8.4",
+    "source-map-support": "^0.5.19",
+    "tmp": "^0.2.1"
   },
   "devDependencies": {
-    "@types/jest": "26.x",
-    "@types/ncp": "2.x",
-    "@types/node": "10.x",
-    "@types/page-icon": "0.x",
-    "@types/shelljs": "0.x",
-    "@types/tmp": "0.x",
-    "@typescript-eslint/eslint-plugin": "4.x",
-    "@typescript-eslint/parser": "4.x",
-    "eslint": "7.x",
-    "eslint-config-prettier": "7.x",
-    "eslint-plugin-prettier": "3.x",
-    "jest": "26.x",
-    "prettier": "2.x",
-    "rimraf": "3.x",
-    "ts-loader": "8.x",
-    "typescript": "4.x",
-    "webpack": "5.x",
-    "webpack-cli": "4.x"
+    "@types/jest": "^26.0.20",
+    "@types/ncp": "^2.0.4",
+    "@types/node": "^10.17.54",
+    "@types/page-icon": "^0.3.3",
+    "@types/shelljs": "^0.8.8",
+    "@types/tmp": "^0.2.0",
+    "@typescript-eslint/eslint-plugin": "^4.15.2",
+    "@typescript-eslint/parser": "^4.15.2",
+    "eslint": "^7.20.0",
+    "eslint-config-prettier": "^7.2.0",
+    "eslint-plugin-prettier": "^3.3.1",
+    "jest": "^26.6.3",
+    "prettier": "^2.2.1",
+    "rimraf": "^3.0.2",
+    "ts-loader": "^8.0.17",
+    "typescript": "^4.2.2",
+    "webpack": "^5.24.2",
+    "webpack-cli": "^4.5.0"
   },
   "jest": {
     "collectCoverage": true,